Zoom lens system, interchangeable lens apparatus and camera system

ABSTRACT

A zoom lens system is provided that includes a compactly constructed focusing lens unit and that has a suppressed change in the image magnification at the time of movement of a focusing lens unit. The zoom lens system, in order from an object side to an image side, comprises at least: a first lens unit having positive optical power; a second lens unit having negative optical power; a third lens unit having negative optical power; and an aperture diaphragm. At the time of zooming, the zoom lens system moves the first to third lens units so that intervals between these lens units vary. At the time of focusing from an infinity in-focus condition to a close-point object in-focus condition, the zoom lens system moves the third lens unit to the object side.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a zoom lens system and, in particular, to a zoom lens system suitable for an imaging lens system employed in an interchangeable lens apparatus in a so-called interchangeable-lens type digital camera system (simply referred to as a “camera system”, in some cases hereinafter). Further, the present invention relates to an interchangeable lens apparatus and a camera system that employ this zoom lens system.

2. Description of the Background Art

In recent years, interchangeable-lens type digital camera systems are spreading rapidly. Such an interchangeable-lens type digital camera system has: a camera body employing an image sensor composed of a CCD (Charge Coupled Device), a CMOS (Complementary Metal-Oxide Semiconductor) or the like; and an interchangeable lens apparatus employing an imaging lens system for forming an optical image on the light receiving plane of the image sensor. Zoom lens systems applicable to such a camera system are disclosed in Japanese Laid-Open Patent Publication Nos. 2005-284097, 2005-352057, 2006-221092, 2005-316396, 2006-267425, 2007-219315, 2008-3195 and 2008-15251.

On the other hand, camera systems are known that have the function (referred to as a “live view function”, hereinafter) of displaying image data acquired by a shooting lens system and an image sensor onto a display apparatus such as a liquid crystal display in the camera body (e.g., Japanese Laid-Open Patent Publication Nos. 2000-111789 and 2000-333064).

In the camera systems described in Japanese Laid-Open Patent Publication Nos. 2000-111789 and 2000-333064, focusing operation is performed by a contrast AF method when the live view function is active. The contrast AF indicates focusing operation performed on the basis of a contrast value of image data outputted from the image sensor. The operation of contrast AF is described below.

First, a camera system oscillates a focusing lens unit in optical axis directions at a high speed (referred to as “wobbling”, hereinafter) so as to detect the direction of deviation from an in-focus condition. After the wobbling, the camera system detects a signal component in a particular frequency band of the image region from the output signal of the image sensor, and then calculates the optimal position for the focusing lens unit that realizes an in-focus condition. After that, the camera system moves the focusing lens unit to the optimal position, so that the focusing operation is completed. When focusing operation is to be performed continuously in the case of shooting a video or the like, the camera system repeats this series of operation.

In general, for the purpose of avoiding uneasiness that could be caused by flicker and the like, displaying of a video is performed at a high speed approximately of 30 frames per second or the like. Thus, basically, video image taking in the interchangeable-lens type digital camera system need also be performed at 30 frames per second. Accordingly, the focusing lens unit need be driven at a high speed of 30 Hz at the time of wobbling.

Nevertheless, when the focusing lens unit is heavier, a motor or an actuator of larger size is necessary for moving the focusing lens unit at a high speed. This causes a problem that the lens barrel has an excessively large outer diameter. Then, in each of the zoom lens systems described in the above-mentioned patent documents, the focusing lens unit is hardly of light weight.

Further, it should be noted that in interchangeable-lens type digital camera systems, the size of the image corresponding to a photographic object varies in association with wobbling. The variation in the size of the image is caused mainly by the fact that the movement of the focusing lens unit in the optical axis directions generates a change in the focal length of the entire lens system. Then, when a large change in the image taking magnification is generated in association with wobbling, the person who takes an image feels uneasiness.

SUMMARY OF THE INVENTION

An object of the present invention is to provide: a zoom lens system that includes a compactly constructed focusing lens unit and that has a suppressed change in the image magnification at the time of movement of a focusing lens unit; and an interchangeable lens apparatus and a camera system that employ this zoom lens system.

The zoom lens system according to the present invention, in order from an object side to an image side, comprising at least: a first lens unit having positive optical power; a second lens unit having negative optical power; a third lens unit having negative optical power; and an aperture diaphragm. At the time of zooming, the first lens unit, the second lens unit and the third lens unit move so that intervals between these lens units vary. At the time of focusing from an infinity in-focus condition to a close-point object in-focus condition, the third lens unit moves to the object side.

The interchangeable lens apparatus according to the present invention comprises: a zoom lens system described above; and a camera mount section connected to a camera body provided with an image sensor for receiving an optical image formed by the zoom lens system and then converting the optical image into an electric image signal.

The camera system according to the present invention comprises: an interchangeable lens apparatus that includes the zoom lens system described above; and a camera body that is connected to the interchangeable lens apparatus via a camera mount section in an attachable and detachable manner and that includes an image sensor for receiving an optical image formed by the zoom lens system and then converting the optical image into an electric image signal.

According to the present invention, a zoom lens system that includes a compactly constructed focusing lens unit and that has a suppressed change in the image magnification at the time of movement of a focusing lens unit, an interchangeable lens apparatus and a camera system that employ this zoom lens system can be provided.

These and other objects, features, aspects and effects of the present invention will become clearer on the basis of the following detailed description with reference to the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a lens arrangement diagram showing an infinity in-focus condition of a zoom lens system according to Embodiment 1 (Example 1);

FIG. 2 is a longitudinal aberration diagram showing an infinity in-focus condition of a zoom lens system according to Example 1;

FIG. 3 is a longitudinal aberration diagram showing a close-point in-focus condition of a zoom lens system according to Example 1;

FIG. 4 is a lateral aberration diagram in a basic state where image blur compensation is not performed and in an image blur compensation state at a telephoto limit of a zoom lens system according to Example 1;

FIG. 5 is a lens arrangement diagram showing an infinity in-focus condition of a zoom lens system according to Embodiment 2 (Example 2);

FIG. 6 is a longitudinal aberration diagram showing an infinity in-focus condition of a zoom lens system according to Example 2;

FIG. 7 is a longitudinal aberration diagram showing a close-point in-focus condition of a zoom lens system according to Example 2;

FIG. 8 is a lateral aberration diagram in a basic state where image blur compensation is not performed and in an image blur compensation state at a telephoto limit of a zoom lens system according to Example 2;

FIG. 9 is a lens arrangement diagram showing an infinity in-focus condition of a zoom lens system according to Embodiment 3 (Example 3);

FIG. 10 is a longitudinal aberration diagram showing an infinity in-focus condition of a zoom lens system according to Example 3;

FIG. 11 is a longitudinal aberration diagram showing a close-point in-focus condition of a zoom lens system according to Example 3;

FIG. 12 is a lateral aberration diagram in a basic state where image blur compensation is not performed and in an image blur compensation state at a telephoto limit of a zoom lens system according to Example 3;

FIG. 13 is a lens arrangement diagram showing an infinity in-focus condition of a zoom lens system according to Embodiment 4 (Example 4);

FIG. 14 is a longitudinal aberration diagram showing an infinity in-focus condition of a zoom lens system according to Example 4;

FIG. 15 is a longitudinal aberration diagram showing a close-point in-focus condition of a zoom lens system according to Example 4;

FIG. 16 is a lateral aberration diagram in a basic state where image blur compensation is not performed and in an image blur compensation state at a telephoto limit of a zoom lens system according to Example 4;

FIG. 17 is a lens arrangement diagram showing an infinity in-focus condition of a zoom lens system according to Embodiment 5 (Example 5);

FIG. 18 is a longitudinal aberration diagram showing an infinity in-focus condition of a zoom lens system according to Example 5;

FIG. 19 is a longitudinal aberration diagram showing a close-point in-focus condition of a zoom lens system according to Example 5;

FIG. 20 is a lateral aberration diagram in a basic state where image blur compensation is not performed and in an image blur compensation state at a telephoto limit of a zoom lens system according to Example 5;

FIG. 21 is a lens arrangement diagram showing an infinity in-focus condition of a zoom lens system according to Embodiment 6 (Example 6);

FIG. 22 is a longitudinal aberration diagram showing an infinity in-focus condition of a zoom lens system according to Example 6;

FIG. 23 is a longitudinal aberration diagram showing a close-point in-focus condition of a zoom lens system according to Example 6;

FIG. 24 is a lateral aberration diagram in a basic state where image blur compensation is not performed and in an image blur compensation state at a telephoto limit of a zoom lens system according to Example 6;

FIG. 25 is a lens arrangement diagram showing an infinity in-focus condition of a zoom lens system according to Embodiment 7 (Example 7);

FIG. 26 is a longitudinal aberration diagram showing an infinity in-focus condition of a zoom lens system according to Example 7;

FIG. 27 is a longitudinal aberration diagram showing a close-point in-focus condition of a zoom lens system according to Example 7;

FIG. 28 is a lateral aberration diagram in a basic state where image blur compensation is not performed and in an image blur compensation state at a telephoto limit of a zoom lens system according to Example 7;

FIG. 29 is a lens arrangement diagram showing an infinity in-focus condition of a zoom lens system according to Embodiment 8 (Example 8);

FIG. 30 is a longitudinal aberration diagram showing an infinity in-focus condition of a zoom lens system according to Example 8;

FIG. 31 is a longitudinal aberration diagram showing a close-point in-focus condition of a zoom lens system according to Example 8;

FIG. 32 is a lateral aberration diagram in a basic state where image blur compensation is not performed and in an image blur compensation state at a telephoto limit of a zoom lens system according to Example 8;

FIG. 33 is a lens arrangement diagram showing an infinity in-focus condition of a zoom lens system according to Embodiment 9 (Example 9);

FIG. 34 is a longitudinal aberration diagram showing an infinity in-focus condition of a zoom lens system according to Example 9;

FIG. 35 is a longitudinal aberration diagram showing a close-point in-focus condition of a zoom lens system according to Example 9;

FIG. 36 is a lateral aberration diagram in a basic state where image blur compensation is not performed and in an image blur compensation state at a telephoto limit of a zoom lens system according to Example 9;

FIG. 37 is a lens arrangement diagram showing an infinity in-focus condition of a zoom lens system according to Embodiment 10 (Example 10);

FIG. 38 is a longitudinal aberration diagram showing an infinity in-focus condition of a zoom lens system according to Example 10;

FIG. 39 is a longitudinal aberration diagram showing a close-point in-focus condition of a zoom lens system according to Example 10;

FIG. 40 is a lateral aberration diagram in a basic state where image blur compensation is not performed and in an image blur compensation state at a telephoto limit of a zoom lens system according to Example 10;

FIG. 41 is a lens arrangement diagram showing an infinity in-focus condition of a zoom lens system according to Embodiment 11 (Example 11);

FIG. 42 is a longitudinal aberration diagram showing an infinity in-focus condition of a zoom lens system according to Example 11;

FIG. 43 is a longitudinal aberration diagram showing a close-point in-focus condition of a zoom lens system according to Example 11;

FIG. 44 is a lateral aberration diagram in a basic state where image blur compensation is not performed and in an image blur compensation state at a telephoto limit of a zoom lens system according to Example 11; and

FIG. 45 is a block diagram of a camera system according to Embodiment 12.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Each of FIGS. 1, 5, 9, 13, 17, 21, 25, 29, 33, 37 and 41 shows a zoom lens system in an infinity in-focus condition.

In each Fig., part (a) shows a lens configuration at a wide-angle limit (in the minimum focal length condition: focal length f_(W)), part (b) shows a lens configuration at a middle position (in an intermediate focal length condition: focal length f_(M)=√(f_(W)*f_(T))), and part (c) shows a lens configuration at a telephoto limit (in the maximum focal length condition: focal length f_(T)). Further, in each Fig., each bent arrow located between part (a) and part (b) indicates a line obtained by connecting the positions of each lens unit respectively at a wide-angle limit, a middle position and a telephoto limit. In the part between the wide-angle limit and the middle position and the part between the middle position and the telephoto limit, the positions are connected simply with a straight line, and hence this line does not indicate actual motion of each lens unit. Moreover, in each Fig., an arrow imparted to a lens unit indicates focusing from an infinity in-focus condition to a close-object in-focus condition. That is, the arrow indicates the moving direction at the time of focusing from an infinity in-focus condition to a close-object in-focus condition.

Further, in FIGS. 1, 5, 9, 13, 17, 21, 25, 29, 33, 37 and 41, an asterisk “*” imparted to a particular surface indicates that the surface is aspheric. In each Fig., symbol (+) or (−) imparted to the symbol of each lens unit corresponds to the sign of the optical power of the lens unit. Further, in each Fig., the straight line located on the most right-hand side indicates the position of the image surface S.

Embodiment 1

The zoom lens system according to Embodiment 1, in order from the object side to the image side, comprises a first lens unit G1 having positive optical power, a second lens unit G2 having negative optical power, a third lens unit G3 having negative optical power, a lens unit G4A having positive optical power, and a lens unit G4B having positive optical power. The lens units G4A and G4B constitute a fourth lens unit G4.

The first lens unit G1, in order from the object side to the image side, comprises: a negative meniscus first lens element L1 with the convex surface facing the object side; and a positive meniscus second lens element L2 with the convex surface facing the object side. The first lens element L1 and the second lens element L2 are cemented with each other.

The second lens unit G2, in order from the object side to the image side, comprises: a negative meniscus third lens element L3 with the convex surface facing the object side; a bi-concave fourth lens element L4; and a bi-convex fifth lens element L5.

The third lens unit G3 is composed of a negative meniscus sixth lens element L6 with the convex surface facing the image side.

The lens unit G4A is composed of a bi-convex seventh lens element L7. The image side surface of the seventh lens element L7 is aspheric.

The lens unit G4B, in order from the object side to the image side, comprises: a bi-convex eighth lens element L8; a negative meniscus ninth lens element L9 with the convex surface facing the image side; a negative meniscus tenth lens element L10 with the convex surface facing the object side; and a positive meniscus eleventh lens element L11 with the convex surface facing the object side. The eighth lens element L8 and the ninth lens element L9 are cemented with each other.

In zooming from a wide-angle limit to a telephoto limit, the first lens unit G1 to the lens unit G4B individually move to the object side. More specifically, in zooming from a wide-angle limit to a telephoto limit, the individual lens units move along the optical axis such that the interval between the first lens unit G1 and the second lens unit G2 should increase, the interval between the second lens unit G2 and the third lens unit G3 should decrease and then increase, and the interval between the third lens unit G3 and the lens unit G4A should decrease. The aperture diaphragm A moves to the object side together with the lens unit G4B.

Further, at the time of focusing from an infinity in-focus condition to a close-point in-focus condition, the third lens unit G3 moves to the object side along the optical axis.

Further, for the purpose of compensation of image blur caused by vibration applied to the entire system, the third lens unit G3 moves in a direction perpendicular to the optical axis.

Embodiment 2

The zoom lens system according to Embodiment 2, in order from the object side to the image side, comprises a first lens unit G1 having positive optical power, a second lens unit G2 having negative optical power, a third lens unit G3 having negative optical power, a lens unit G4A having positive optical power, and a lens unit G4B having positive optical power. The lens units G4A and G4B constitute a fourth lens unit G4.

The first lens unit G1, in order from the object side to the image side, comprises: a negative meniscus first lens element L1 with the convex surface facing the object side; and a positive meniscus second lens element L2 with the convex surface facing the object side. The first lens element L1 and the second lens element L2 are cemented with each other with an adhesive layer in between.

The second lens unit G2, in order from the object side to the image side, comprises: a negative meniscus third lens element L3 with the convex surface facing the object side; a bi-concave fourth lens element L4; and a bi-convex fifth lens element L5.

The third lens unit G3 is composed of a negative meniscus sixth lens element L6 with the convex surface facing the image side.

The lens unit G4A is composed of a bi-convex seventh lens element L7. The image side surface of the seventh lens element L7 is aspheric.

The lens unit G4B, in order from the object side to the image side, comprises: a bi-convex eighth lens element L8; a bi-concave ninth lens element L9; a bi-convex tenth lens element L10; a negative meniscus eleventh lens element L11 with the convex surface facing the image side; and a positive meniscus twelfth lens element L12 with the convex surface facing the object side. The eighth lens element L8 and the ninth lens element L9 are cemented with each other with an adhesive layer in between.

In zooming from a wide-angle limit to a telephoto limit, the first lens unit G1 to the lens unit G4B individually move to the object side. More specifically, in zooming from a wide-angle limit to a telephoto limit, the individual lens units move along the optical axis such that the interval between the first lens unit G1 and the second lens unit G2 should increase, the interval between the second lens unit G2 and the third lens unit G3 should decrease and then increase, and the interval between the third lens unit G3 and the lens unit G4A should decrease. The aperture diaphragm A moves to the object side together with the lens unit G4B.

Further, at the time of focusing from an infinity in-focus condition to a close-point in-focus condition, the third lens unit G3 moves to the object side along the optical axis.

Further, for the purpose of compensation of image blur caused by vibration applied to the entire system, the third lens unit G3 moves in a direction perpendicular to the optical axis.

Embodiment 3

The zoom lens system according to Embodiment 3, in order from the object side to the image side, comprises a first lens unit G1 having positive optical power, a second lens unit G2 having negative optical power, a third lens unit G3 having negative optical power, a lens unit G4A having positive optical power, and a lens unit G4B having positive optical power. The lens units G4A and G4B constitute a fourth lens unit G4.

The first lens unit G1, in order from the object side to the image side, comprises: a negative meniscus first lens element L1 with the convex surface facing the object side; and a positive meniscus second lens element L2 with the convex surface facing the object side. The first lens element L1 and the second lens element L2 are cemented with each other with an adhesive layer in between.

The second lens unit G2, in order from the object side to the image side, comprises: a negative meniscus third lens element L3 with the convex surface facing the object side; a bi-concave fourth lens element L4; and a bi-convex fifth lens element L5.

The third lens unit G3 is composed of a negative meniscus sixth lens element L6 with the convex surface facing the image side.

The lens unit G4A is composed of a positive meniscus seventh lens element L7 with the convex surface facing the image side.

The lens unit G4B, in order from the object side to the image side, comprises: a bi-convex eighth lens element L8; a negative meniscus ninth lens element L9 with the convex surface facing the image side; a bi-convex tenth lens element L10; a bi-concave eleventh lens element L11; and a bi-convex twelfth lens element L12. The eighth lens element L8 and the ninth lens element L9 are cemented with each other with an adhesive layer in between. The object side surface of the tenth lens element L10 is aspheric.

In zooming from a wide-angle limit to a telephoto limit, the first lens unit G1 to the lens unit G4B individually move to the object side. More specifically, in zooming from a wide-angle limit to a telephoto limit, the individual lens units move along the optical axis such that the interval between the first lens unit G1 and the second lens unit G2 should increase, the interval between the second lens unit G2 and the third lens unit G3 should decrease and then increase, and the interval between the third lens unit G3 and the lens unit G4A should decrease. The aperture diaphragm A moves to the object side together with the lens unit G4B.

Further, at the time of focusing from an infinity in-focus condition to a close-point in-focus condition, the third lens unit G3 moves to the object side along the optical axis.

Further, for the purpose of compensation of image blur caused by vibration applied to the entire system, the third lens unit G3 moves in a direction perpendicular to the optical axis.

Embodiment 4

The zoom lens system according to Embodiment 4, in order from the object side to the image side, comprises a first lens unit G1 having positive optical power, a second lens unit G2 having negative optical power, a third lens unit G3 having negative optical power, a lens unit G4A having positive optical power, and a lens unit G4B having positive optical power. The lens units G4A and G4B constitute a fourth lens unit G4.

The first lens unit G1, in order from the object side to the image side, comprises: a negative meniscus first lens element L1 with the convex surface facing the object side; and a positive meniscus second lens element L2 with the convex surface facing the object side. The first lens element L1 and the second lens element L2 are cemented with each other with an adhesive layer in between.

The second lens unit G2, in order from the object side to the image side, comprises: a negative meniscus third lens element L3 with the convex surface facing the object side; a bi-concave fourth lens element L4; and a bi-convex fifth lens element L5.

The third lens unit G3 is composed of a negative meniscus sixth lens element L6 with the convex surface facing the image side.

The lens unit G4A is composed of a positive meniscus seventh lens element L7 with the convex surface facing the image side.

The lens unit G4B, in order from the object side to the image side, comprises: a bi-convex eighth lens element L8; a negative meniscus ninth lens element L9 with the convex surface facing the image side; a bi-convex tenth lens element L10; a bi-concave eleventh lens element L11; and a bi-convex twelfth lens element L12. The eighth lens element L8 and the ninth lens element L9 are cemented with each other with an adhesive layer in between. The tenth lens element L10 and the eleventh lens element L11 are also cemented with each other with an adhesive layer in between. The object side surface of the tenth lens element L10 is aspheric.

In zooming from a wide-angle limit to a telephoto limit, the first lens unit G1 to the lens unit G4B individually move to the object side. More specifically, in zooming from a wide-angle limit to a telephoto limit, the individual lens units move along the optical axis such that the interval between the first lens unit G1 and the second lens unit G2 should increase, the interval between the second lens unit G2 and the third lens unit G3 should decrease and then increase, and the interval between the third lens unit G3 and the lens unit G4A should decrease. The aperture diaphragm A moves to the object side together with the lens unit G4B.

Further, at the time of focusing from an infinity in-focus condition to a close-point in-focus condition, the third lens unit G3 moves to the object side along the optical axis.

Further, for the purpose of compensation of image blur caused by vibration applied to the entire system, the lens unit G4A moves in a direction perpendicular to the optical axis.

Embodiment 5

The zoom lens system according to Embodiment 5, in order from the object side to the image side, comprises a first lens unit G1 having positive optical power, a second lens unit G2 having negative optical power, a third lens unit G3 having negative optical power, a lens unit G4A having positive optical power, and a lens unit G4B having positive optical power. The lens units G4A and G4B constitute a fourth lens unit G4.

The first lens unit G1, in order from the object side to the image side, comprises: a negative meniscus first lens element L1 with the convex surface facing the object side; and a positive meniscus second lens element L2 with the convex surface facing the object side. The first lens element L1 and the second lens element L2 are cemented with each other with an adhesive layer in between.

The second lens unit G2, in order from the object side to the image side, comprises: a negative meniscus third lens element L3 with the convex surface facing the object side; a bi-concave fourth lens element L4; and a bi-convex fifth lens element L5.

The third lens unit G3 is composed of a negative meniscus sixth lens element L6 with the convex surface facing the image side.

The lens unit G4A is composed of a positive meniscus seventh lens element L7 with the convex surface facing the image side.

The lens unit G4B, in order from the object side to the image side, comprises: a bi-convex eighth lens element L8; a bi-concave ninth lens element L9; a bi-convex tenth lens element L10; a negative meniscus eleventh lens element L11 with the convex surface facing the image side; and a bi-convex twelfth lens element L12. The eighth lens element L8 and the ninth lens element L9 are cemented with each other with an adhesive layer in between. The tenth lens element L10 and the eleventh lens element L11 are also cemented with each other with an adhesive layer in between. The object side surface of the tenth lens element L10 is aspheric.

In zooming from a wide-angle limit to a telephoto limit, the first lens unit G1 to the lens unit G4B individually move to the object side. More specifically, in zooming from a wide-angle limit to a telephoto limit, the individual lens units move along the optical axis such that the interval between the first lens unit G1 and the second lens unit G2 should increase, the interval between the second lens unit G2 and the third lens unit G3 should decrease and then increase, and the interval between the third lens unit G3 and the lens unit G4A should decrease. The aperture diaphragm A moves to the object side together with the lens unit G4B.

Further, at the time of focusing from an infinity in-focus condition to a close-point in-focus condition, the third lens unit G3 moves to the object side along the optical axis.

Further, for the purpose of compensation of image blur caused by vibration applied to the entire system, the lens unit G4A moves in a direction perpendicular to the optical axis.

Embodiment 6

Further, the zoom lens system according to Embodiment 6, in order from the object side to the image side, comprises: a first lens unit G1 having positive optical power; a second lens unit G2 having negative optical power; a third lens unit G3 having negative optical power; and a fourth lens unit G4 having positive optical power.

The first lens unit G1, in order from the object side to the image side, comprises: a negative meniscus first lens element L1 with the convex surface facing the object side; and a positive meniscus second lens element L2 with the convex surface facing the object side. The first lens element L1 and the second lens element L2 are cemented with each other with an adhesive layer in between.

The second lens unit G2, in order from the object side to the image side, comprises: a negative meniscus third lens element L3 with the convex surface facing the object side; a bi-concave fourth lens element L4; and a bi-convex fifth lens element L5. The image side surface of the fourth lens element L4 is aspheric.

The third lens unit G3 is composed of a bi-concave sixth lens element L6.

The fourth lens unit G4, in order from the object side to the image side, comprises a bi-convex seventh lens element L7, a bi-convex eighth lens element L8, a bi-concave ninth lens element L9, a bi-convex tenth lens element L10, a bi-concave eleventh lens element L11, and a bi-convex twelfth lens element L12. The eighth lens element L8 and the ninth lens element L9 are cemented with each other with an adhesive layer in between. The tenth lens element L10 and the eleventh lens element L11 are also cemented with each other with an adhesive layer in between. The object side surface of the tenth lens element L10 is aspheric.

In zooming from a wide-angle limit to a telephoto limit, the first lens unit G1 to the fourth lens unit G4 individually move to the object side. More specifically, in zooming from a wide-angle limit to a telephoto limit, the individual lens units move along the optical axis such that the interval between the first lens unit G1 and the second lens unit G2 should increase, the interval between the second lens unit G2 and the third lens unit G3 should decrease and then increase, and the interval between the third lens unit G3 and the fourth lens unit G4 should decrease. The aperture diaphragm A moves to the object side together with the fourth lens unit G4.

Further, at the time of focusing from an infinity in-focus condition to a close-point in-focus condition, the third lens unit G3 moves to the object side along the optical axis.

Further, for the purpose of compensation of image blur caused by vibration applied to the entire system, the third lens unit G3 moves in a direction perpendicular to the optical axis.

Embodiment 7

The zoom lens system according to Embodiment 7, in order from the object side to the image side, comprises a first lens unit G1 having positive optical power, a second lens unit G2 having negative optical power, a third lens unit G3 having negative optical power, a fourth lens unit G4 having positive optical power, a lens unit G5A having positive optical power, and a lens unit G5B having negative optical power. The lens units G5A and G5B constitute a fifth lens unit G5.

The first lens unit G1, in order from the object side to the image side, comprises: a negative meniscus first lens element L1 with the convex surface facing the object side; a positive meniscus second lens element L2 with the convex surface facing the object side; and a positive meniscus third lens element L3 with the convex surface facing the object side. The first lens element L1 and the second lens element L2 are cemented with each other.

The second lens unit G2, in order from the object side to the image side, comprises: a negative meniscus fourth lens element L4 with the convex surface facing the object side; a bi-concave fifth lens element L5; and a positive meniscus sixth lens element L6 with the convex surface facing the object side.

The third lens unit G3, in order from the object side to the image side, comprises: a bi-concave seventh lens element L7; and a positive meniscus eighth lens element L8 with the convex surface facing the object side.

The fourth lens unit G4, in order from the object side to the image side, comprises: a bi-convex ninth lens element L9; a positive meniscus tenth lens element L10 with the convex surface facing the object side; and a negative meniscus eleventh lens element L11 with the convex surface facing the object side. The object side surface of the tenth lens element L10 is aspheric.

The lens unit G5A, in order from the object side to the image side, comprises: a negative meniscus twelfth lens element L12 with the convex surface facing the object side; and a bi-convex thirteenth lens element L13. The twelfth lens element L12 and the thirteenth lens element L13 are cemented with each other. The image side surface of the thirteenth lens element L13 is aspheric.

The lens unit G5B, in order from the object side to the image side, comprises: a bi-concave fourteenth lens element L14; a bi-convex fifteenth lens element L15; and a negative meniscus sixteenth lens element L16 with the convex surface facing the image side. The object side surface of the fifteenth lens element L15 is aspheric.

In zooming from a wide-angle limit to a telephoto limit, the first lens unit G1 to the lens unit G5B individually move to the object side. More specifically, in zooming from a wide-angle limit to a telephoto limit, the individual lens units move along the optical axis such that the interval between the first lens unit G1 and the second lens unit G2 should increase, the interval between the second lens unit G2 and the third lens unit G3 should decrease and then increase, the interval between the third lens unit G3 and the fourth lens unit G4 should decrease, and the interval between the fourth lens unit G4 and the lens unit G5A should decrease. The aperture diaphragm A moves to the object side together with the fourth lens unit G4.

Further, at the time of focusing from an infinity in-focus condition to a close-point in-focus condition, the third lens unit G3 moves to the object side along the optical axis.

Further, for the purpose of compensation of image blur caused by vibration applied to the entire system, the lens unit G5A moves in a direction perpendicular to the optical axis.

Embodiment 8

The zoom lens system according to Embodiment 8, in order from the object side to the image side, comprises a first lens unit G1 having positive optical power, a second lens unit G2 having negative optical power, a third lens unit G3 having negative optical power, a lens unit G4A having positive optical power, a lens unit G4B having negative optical power, and a fifth lens unit G5 having positive optical power. The lens units G4A and G4B constitute a fourth lens unit G4.

The first lens unit G1, in order from the object side to the image side, comprises: a negative meniscus first lens element L1 with the convex surface facing the object side; a positive meniscus second lens element L2 with the convex surface facing the object side; and a positive meniscus third lens element L3 with the convex surface facing the object side. The first lens element L1 and the second lens element L2 are cemented with each other.

The second lens unit G2, in order from the object side to the image side, comprises: a negative meniscus fourth lens element L4 with the convex surface facing the object side; a bi-concave fifth lens element L5; and a bi-convex sixth lens element L6.

The third lens unit G3 is composed of a negative meniscus seventh lens element L7 with the convex surface facing the image side.

The lens unit G4A, in order from the object side to the image side, comprises a bi-convex eighth lens element L8, a bi-convex ninth lens element L9, a bi-concave tenth lens element L10 and a bi-convex eleventh lens element L11. The ninth lens element L9 and the tenth lens element L10 are cemented with each other with an adhesive layer in between. The image side surface of the eighth lens element L8 is aspheric.

The lens unit G4B, in order from the object side to the image side, comprises: a positive meniscus twelfth lens element L12 with the convex surface facing the image side; and a bi-concave thirteenth lens element L13. The twelfth lens element L12 and the thirteenth lens element L13 are cemented with each other.

The fifth lens unit G5, in order from the object side to the image side, comprises: a positive meniscus fourteenth lens element L14 with the convex surface facing the image side; a negative meniscus fifteenth lens element L15 with the convex surface facing the image side; a bi-convex sixteenth lens element L16; and a negative meniscus seventeenth lens element L17 with the convex surface facing the image side. The sixteenth lens element L16 and the seventeenth lens element L17 are cemented with each other with an adhesive layer in between. The image side surface of the fourteenth lens element L14 is aspheric.

In zooming from a wide-angle limit to a telephoto limit, the first lens unit G1 to the fifth lens unit G5 individually move to the object side. More specifically, in zooming from a wide-angle limit to a telephoto limit, the individual lens units move along the optical axis such that the interval between the first lens unit G1 and the second lens unit G2 should increase, the interval between the second lens unit G2 and the third lens unit G3 should increase, the interval between the third lens unit G3 and the lens unit G4A should decrease, and the interval between the lens unit G4B and the fifth lens unit G5 should increase. The aperture diaphragm A moves to the object side together with the lens unit G4A.

Further, at the time of focusing from an infinity in-focus condition to a close-point in-focus condition, the third lens unit G3 moves to the object side along the optical axis.

Further, for the purpose of compensation of image blur caused by vibration applied to the entire system, the lens unit G4B moves in a direction perpendicular to the optical axis.

Embodiment 9

The zoom lens system according to Embodiment 9, in order from the object side to the image side, comprises a first lens unit G1 having positive optical power, a second lens unit G2 having negative optical power, a third lens unit G3 having negative optical power, a lens unit G4A having positive optical power, a lens unit G4B having negative optical power, and a fifth lens unit G5 having positive optical power. The lens units G4A and G4B constitute a fourth lens unit G4.

The first lens unit G1, in order from the object side to the image side, comprises: a negative meniscus first lens element L1 with the convex surface facing the object side; and a positive meniscus second lens element L2 with the convex surface facing the object side. The first lens element L1 and the second lens element L2 are cemented with each other with an adhesive layer in between.

The second lens unit G2, in order from the object side to the image side, comprises: a negative meniscus third lens element L3 with the convex surface facing the object side; a negative meniscus fourth lens element L4 with the convex surface facing the object side; and a positive meniscus fifth lens element L5 with the convex surface facing the object side.

The third lens unit G3 is composed of a negative meniscus sixth lens element L6 with the convex surface facing the image side.

The lens unit G4A, in order from the object side to the image side, comprises: a bi-convex seventh lens element L7; and a negative meniscus eighth lens element L8 with the convex surface facing the image side. The seventh lens element L7 and the eighth lens element L8 are cemented with each other with an adhesive layer in between.

The lens unit G4B is composed of a negative meniscus ninth lens element L9 with the convex surface facing the image side.

The fifth lens unit G5, in order from the object side to the image side, comprises: a bi-convex tenth lens element L10; a bi-convex eleventh lens element L11; and a negative meniscus twelfth lens element L12 with the convex surface facing the object side. The object side surface of the tenth lens element L10 is aspheric.

In zooming from a wide-angle limit to a telephoto limit, the first lens unit G1 to the fifth lens unit G5 individually move to the object side. More specifically, in zooming from a wide-angle limit to a telephoto limit, the individual lens units move along the optical axis such that the interval between the first lens unit G1 and the second lens unit G2 should increase, the interval between the second lens unit G2 and the third lens unit G3 should increase, the interval between the third lens unit G3 and the lens unit G4A should decrease, and the interval between the lens unit G4B and the fifth lens unit G5 should decrease. The aperture diaphragm A moves to the object side together with the lens unit G4A.

Further, at the time of focusing from an infinity in-focus condition to a close-point in-focus condition, the third lens unit G3 moves to the object side along the optical axis.

Further, for the purpose of compensation of image blur caused by vibration applied to the entire system, the lens unit G4B moves in a direction perpendicular to the optical axis.

Embodiment 10

The zoom lens system according to Embodiment 10, in order from the object side to the image side, comprises a first lens unit G1 having positive optical power, a second lens unit G2 having negative optical power, a third lens unit G3 having negative optical power, a lens unit G4A having positive optical power, a lens unit G4B having negative optical power, and a lens unit G4C having positive optical power. The lens units G4A to G4C constitute a fourth lens unit G4.

The first lens unit G1, in order from the object side to the image side, comprises: a negative meniscus first lens element L1 with the convex surface facing the object side; and a positive meniscus second lens element L2 with the convex surface facing the object side. The first lens element L1 and the second lens element L2 are cemented with each other with an adhesive layer in between.

The second lens unit G2, in order from the object side to the image side, comprises: a negative meniscus third lens element L3 with the convex surface facing the object side; a bi-concave fourth lens element L4; and a bi-convex fifth lens element L5.

The third lens unit G3 is composed of a negative meniscus sixth lens element L6 with the convex surface facing the image side.

The lens unit G4A, in order from the object side to the image side, comprises: a positive meniscus seventh lens element

L7 with the convex surface facing the image side; a bi-convex eighth lens element L8; and a bi-concave ninth lens element L9. The eighth lens element L8 and the ninth lens element L9 are cemented with each other with an adhesive layer in between.

The lens unit G4B is composed of a negative meniscus tenth lens element L10 with the convex surface facing the object side.

The lens unit G4C comprises: a bi-convex eleventh lens element L11; and a negative meniscus twelfth lens element L12 with the convex surface facing the image side. The eleventh lens element L11 and the twelfth lens element L12 are cemented with each other with an adhesive layer in between. The object side surface of the eleventh lens element L11 is aspheric.

In zooming from a wide-angle limit to a telephoto limit, the first lens unit G1 to the lens unit G4C individually move to the object side. More specifically, in zooming from a wide-angle limit to a telephoto limit, the individual lens units move along the optical axis such that the interval between the first lens unit G1 and the second lens unit G2 should increase, the interval between the second lens unit G2 and the third lens unit G3 should decrease and then increase, and the interval between the third lens unit G3 and the lens unit G4A should decrease. The aperture diaphragm A moves to the object side together with the lens unit G4A.

Further, at the time of focusing from an infinity in-focus condition to a close-point in-focus condition, the third lens unit G3 moves to the object side along the optical axis.

Further, for the purpose of compensation of image blur caused by vibration applied to the entire system, the lens unit G4B moves in a direction perpendicular to the optical axis.

Embodiment 11

The zoom lens system according to Embodiment 11, in order from the object side to the image side, comprises a first lens unit G1 having positive optical power, a second lens unit G2 having negative optical power, a third lens unit G3 having negative optical power, a lens unit G4A having positive optical power, a lens unit G4B having negative optical power, and a lens unit G4C having positive optical power. The lens units G4A to G4C constitute a fourth lens unit G4.

The first lens unit G1, in order from the object side to the image side, comprises: a negative meniscus first lens element L1 with the convex surface facing the object side; and a positive meniscus second lens element L2 with the convex surface facing the object side. The first lens element L1 and the second lens element L2 are cemented with each other with an adhesive layer in between.

The second lens unit G2, in order from the object side to the image side, comprises: a negative meniscus third lens element L3 with the convex surface facing the object side; a bi-concave fourth lens element L4; and a bi-convex fifth lens element L5.

The third lens unit G3 is composed of a negative meniscus sixth lens element L6 with the convex surface facing the image side.

The lens unit G4A, in order from the object side to the image side, comprises: a positive meniscus seventh lens element L7 with the convex surface facing the image side; a bi-convex eighth lens element L8; and a bi-concave ninth lens element L9. The eighth lens element L8 and the ninth lens element L9 are cemented with each other with an adhesive layer in between.

The lens unit G4B is composed of a negative meniscus tenth lens element L10 with the convex surface facing the object side.

The lens unit G4C, in order from the object side to the image side, comprises: a bi-convex eleventh lens element L11; and a negative meniscus twelfth lens element L12 with the convex surface facing the image side. The eleventh lens element L11 and the twelfth lens element L12 are cemented with each other with an adhesive layer in between. The object side surface of the eleventh lens element L11 is aspheric.

In zooming from a wide-angle limit to a telephoto limit, the first lens unit G1 to the lens unit G4C individually move to the object side. More specifically, in zooming from a wide-angle limit to a telephoto limit, the individual lens units move along the optical axis such that the interval between the first lens unit G1 and the second lens unit G2 should increase, the interval between the second lens unit G2 and the third lens unit G3 should decrease and then increase, and the interval between the third lens unit G3 and the lens unit G4A should decrease. The aperture diaphragm A moves to the object side together with the lens unit G4A.

Further, at the time of focusing from an infinity in-focus condition to a close-point in-focus condition, the third lens unit G3 moves to the object side along the optical axis.

Further, for the purpose of compensation of image blur caused by vibration applied to the entire system, the lens unit G4B moves in a direction perpendicular to the optical axis.

The zoom lens system according to each of the above-mentioned embodiments includes, in order from an object side to an image side: a first lens unit having positive optical power; a second lens unit having negative optical power; a third lens unit having negative optical power; and an aperture diaphragm. At the time of zooming, each zoom lens system moves the first to third lens units so that intervals between these lens units vary. Further at the time of focusing from an infinity in-focus condition to a close-point object in-focus condition, each zoom lens system moves the third lens unit to the object side. This arrangement of the focusing lens unit reduces the image magnification change generated at the time of focusing.

The following description is given for conditions to be satisfied by the zoom lens system according to each embodiment. Here, in the zoom lens system according to each embodiment, a plurality of conditions to be satisfied are set forth. Thus, a configuration of a zoom lens system that satisfies as many applicable conditions as possible is most preferable. However, when an individual condition is satisfied, a zoom lens system having the corresponding effect can be obtained.

It is preferable that the zoom lens system according to each embodiment satisfies the following condition.

1.2<|f _(F) /f _(W)|<6.0   (1)

(here, f_(T)/f_(w)>3.0)

where,

f_(F) is a focal length of the focusing lens unit,

f_(T) is a focal length of the entire system at a telephoto limit, and

f_(W) is focal length of the entire system at a wide-angle limit.

The condition (1) sets forth the focal length of the focusing lens unit. When the value exceeds the upper limit of the condition (1), the focal length of the focusing lens unit becomes excessively great, and hence the amount of movement at the time of focusing increases. This prevents realization of a compact zoom lens system. In contrast, when the value goes below the lower limit of the condition (1). The focal length of the focusing lens unit becomes excessively small. Thus, aberration fluctuation at the time of focusing becomes excessively large. Accordingly, aberration cannot be compensated by other lens units.

It is preferable that the zoom lens system according to each embodiment satisfies the following condition.

0.10<|f _(F) /f _(T)|<1.8   (2)

(here, f_(T)/f_(W)>3.0)

where,

f_(F) is a focal length of the focusing lens unit,

f_(T) is a focal length of the entire system at a telephoto limit, and

f_(W) is focal length of the entire system at a wide-angle limit.

The condition (2) sets forth the focal length of the focusing lens unit. When the value exceeds the upper limit of the condition (2), the focal length of the focusing lens unit becomes excessively great, and hence the amount of movement at the time of focusing increases. This prevents realization of a compact zoom lens system. In contrast, when the value goes below the lower limit of the condition (2), the focal length of the focusing lens unit becomes excessively small. Thus, aberration fluctuation at the time of focusing becomes excessively large. Further, error sensitivity in the focusing lens unit becomes high. This causes difficulty in assembling and adjustment.

It is preferable that the zoom lens system according to each embodiment satisfies the following condition.

1.00<|f _(F) /f _(NW)|<5.00   (3)

(here, f_(T)/f_(W)>3.0)

where,

f_(F) is a focal length of the focusing lens unit,

f_(NW) is a composite focal length of the focusing lens unit and the negative lens unit in an infinity in-focus condition at a wide-angle limit when the focusing lens unit has negative optical power, or the focal length of the negative lens unit when the focusing lens unit has positive optical power,

f_(T) is a focal length of the entire system at a telephoto limit, and

f_(W) is focal length of the entire system at a wide-angle limit.

The condition (3) sets forth the ratio between the focal length of the focusing lens unit and the focal length of the negative lens unit. When the value exceeds the upper limit of the condition (3), the focal length of the focusing lens unit becomes excessively great, and hence the amount of movement at the time of focusing increases. This prevents realization of a compact zoom lens system. In contrast, when the value goes below the lower limit of the condition (3), aberration fluctuation generated at the time of zooming cannot be compensated by the subsequent lens units. Further, the image magnification change generated in association with the movement of the focusing lens unit becomes excessively large. Thus, this situation is unpreferable.

Among the zoom lens systems according to the individual embodiments, when the negative lens unit is arranged on the image side relative to the lens unit having positive optical power with the interval in between that varies at the time of zooming, it is preferable that the zoom lens system satisfies the following condition.

1.20<β_(NT)/β_(NW)<4.50   (4)

(here, f_(T)/f_(W)>3.0)

where,

β_(NT) is a composite focal length of the focusing lens unit and the negative lens unit in an infinity in-focus condition at a telephoto limit when the focusing lens unit has negative optical power, or a lateral magnification of the negative lens unit at a telephoto limit in an infinity in-focus condition when the focusing lens unit has positive optical power,

β_(NW) is a composite focal length of the focusing lens unit and the negative lens unit in an infinity in-focus condition at a wide-angle limit when the focusing lens unit has negative optical power, or a lateral magnification of the negative lens unit at a wide-angle limit in an infinity in-focus condition when the focusing lens unit has positive optical power,

f_(T) is a focal length of the entire system at a telephoto limit, and

f_(W) is focal length of the entire system at a wide-angle limit.

The condition (4) sets forth the magnification change in the negative lens unit, and substantially indicates the fraction of contribution to zooming. When the value goes outside the range of the condition (4), this situation causes difficulty in zooming itself. Further, aberration fluctuation generated at the time of zooming becomes excessively large, and hence cannot be compensated by other lens units.

Among the zoom lens systems according to the individual embodiments, when the negative lens unit is arranged on the image side relative to the lens unit having positive optical power with the interval in between that varies at the time of zooming, it is preferable that the zoom lens system satisfies the following condition.

0.01<D _(F) /ΣD<0.10   (5)

where,

D_(F) is an axial thickness of the focusing lens unit, and

ΣD is a total of axial thicknesses of the lens elements in the entire system.

The condition (5) sets forth the axial thickness of the focusing lens unit. When the value exceeds the upper limit of the condition (5), the focusing lens unit becomes excessively large. This causes difficulty in focusing such as wobbling suitable for video image taking. In contrast, when the value goes below the lower limit of the condition (5), this situation causes difficulty in ensuring a focal length required for focusing. That is, the amount of movement at the time of focusing becomes excessively large, and hence this situation is unpreferable.

Among the zoom lens systems according to the individual embodiments, when the negative lens unit is arranged on the image side relative to the lens unit having positive optical power with the interval in between that varies at the time of zooming, it is preferable that the zoom lens system satisfies the following condition.

3.20<|f ₁ /f _(NW)|<8.50   (6)

(here, f_(T)/f_(W)>3.0)

where,

f₁ is a focal length of the positive lens unit arranged on the object side of the focusing lens unit,

f_(NW) is a composite focal length of the focusing lens unit and the negative lens unit in an infinity in-focus condition at a wide-angle limit when the focusing lens unit has negative optical power, or the focal length of the negative lens unit when the focusing lens unit has positive optical power,

f_(T) is a focal length of the entire system at a telephoto limit, and

f_(W) is focal length of the entire system at a wide-angle limit.

The condition (6) sets forth the focal length of the positive lens unit arranged on the object side of the focusing lens unit. When the value exceeds the upper limit of the condition (6), aberration fluctuation generated at the time of zooming becomes excessively large. Further, difficulty arises in compensating off-axial aberration, especially, distortion. Thus, this situation is unpreferable. In contrast, when the value goes below the lower limit of the condition (6), aberration fluctuation generated at the time of zooming becomes excessively large. Further, degradation is caused in the performance at the time of focusing on a close object, and hence this situation is unpreferable.

Among the zoom lens systems according to the individual embodiments, in a case that the negative lens unit is arranged on the image side relative to the lens unit having positive optical power with the interval in between that varies at the time of zooming and that the focusing lens unit has negative optical power, it is preferable that the zoom lens system satisfies the following condition.

0.50<D _(FWA) /f _(W)<2.00   (7)

(here, f_(T)/f_(W)>3.0)

where,

D_(FWA) is an axial interval from the vertex of a surface on the most image side of the focusing lens unit to the aperture diaphragm,

f_(T) is a focal length of the entire system at a telephoto limit, and

f_(W) is focal length of the entire system at a wide-angle limit.

The condition (7) sets forth the axial interval from the focusing lens unit to the aperture diaphragm in a case that the focusing lens unit has negative optical power. When the value exceeds the upper limit of the condition (7), the axial interval between the focusing lens unit and the aperture diaphragm becomes excessively great, and hence the focal length of the focusing lens unit increases relatively. This causes difficulty in realizing a compact zoom lens system. Further, when the value exceeds the upper limit of the condition (7), difficulty arises in compensating aberration, especially, spherical aberration fluctuation, generated at the time of focusing. In contrast, when the value goes below the lower limit of the condition (7), the axial interval between the focusing lens unit and the aperture diaphragm becomes excessively small. This causes difficulty in compensating distortion especially at a wide-angle limit, and hence this situation is unpreferable.

Among the zoom lens systems according to the individual embodiments, in a case that the negative lens unit is arranged on the image side relative to the lens unit having positive optical power with the interval in between that varies at the time of zooming and that the focusing lens unit has negative optical power, it is preferable that the zoom lens system satisfies the following condition.

0.10<(D _(F) /f _(W))*(f _(T) /f _(W))<2.00   (8)

(here, f_(T)/f_(W)>3.0)

where,

D_(F) is an axial thickness of the focusing lens unit,

f_(T) is a focal length of the entire system at a telephoto limit, and

f_(W) is focal length of the entire system at a wide-angle limit.

The condition (8) sets forth the axial thickness of the focusing lens unit. When the value exceeds the upper limit of the condition (8), the axial thickness of the focusing lens unit becomes excessively great, and hence the weight of the focusing lens unit increases. Thus, this situation is unpreferable. In contrast, when the value goes below the lower limit of the condition (8), the axial thickness of the focusing lens unit becomes excessively small. This causes difficulty in manufacturing.

Among the zoom lens systems according to the individual embodiments, in a case that the negative lens unit is arranged on the image side relative to the lens unit having positive optical power with the interval in between that varies at the time of zooming and that the focusing lens unit has negative optical power, it is preferable that the zoom lens system satisfies the following condition.

0.02<|D _(F) /f _(F)|<0.15   (9)

(here, f_(T)/f_(W)>3.0)

where,

D_(F) is an axial thickness of the focusing lens unit,

f_(F) is a focal length of the focusing lens unit,

f_(T) is a focal length of the entire system at a telephoto limit, and

f_(W) is focal length of the entire system at a wide-angle limit.

The condition (9) relates to the focal length of the focusing lens unit. When the value exceeds the upper limit of the condition (9), the focal length of the focusing lens unit becomes excessively small. This causes difficulty in compensating aberration fluctuation at the time of focusing. In contrast, when the value goes below the lower limit of the condition (9), the focal length of the focusing lens unit becomes excessively great. Thus, the amount of movement at the time of focusing, especially at the time of wobbling, becomes excessively large. Hence, this situation is unpreferable.

Among the zoom lens systems according to the individual embodiments, in a case that the negative lens unit is arranged on the image side relative to the lens unit having positive optical power with the interval in between that varies at the time of zooming and that the focusing lens unit has negative optical power, it is preferable that the zoom lens system satisfies the following condition.

1.80<|f ₁ /f ₂|4.00   (10)

where,

f₁ is a focal length of the positive lens unit, and

f₂ is a focal length of the negative lens unit.

The condition (10) sets forth the focal length ratio between the positive lens unit and the negative lens unit. When the value exceeds the upper limit of the condition (10), this indicates that the focal length of the positive lens unit is excessively great. This causes difficulty in compensating distortion. In contrast, when the value goes below the lower limit of the condition (10), this indicates that the focal length of the negative lens unit is excessively great. Thus, the amount of movement of the negative lens unit at the time of zooming becomes excessively large, and hence this situation is unpreferable.

Among the zoom lens systems according to the individual embodiments, in a case that the negative lens unit is arranged on the image side relative to the lens unit having positive optical power with the interval in between that varies at the time of zooming and that the focusing lens unit has negative optical power, it is preferable that the zoom lens system satisfies the following condition.

0.40<|f ₂ /f _(F)|<1.80   (11)

where,

f₂ is a focal length of the negative lens unit, and

f_(F) is a focal length of the focusing lens unit.

The condition (11) sets forth the focal length ratio between the focusing lens unit and the negative lens unit. When the value exceeds the upper limit of the condition (11), this indicates that the focal length of the focusing lens unit is excessively small. Thus, the image magnification change at the time of focusing becomes excessively large, and hence this situation is unpreferable. In contrast, when the value goes below the lower limit of the condition (11), this indicates that the focal length of the negative lens unit is excessively small. This causes an increase in aberration fluctuation at the time of zooming, and hence causes difficulty in compensation by other lens units.

Among the zoom lens systems according to the individual embodiments, in a case that the negative lens unit is arranged on the image side relative to the lens unit having positive optical power with the interval in between that varies at the time of zooming and that the focusing lens unit has negative optical power, it is preferable that the zoom lens system satisfies the following condition.

1.50<|f ₁ /f _(F)|<4.00   (12)

where,

f₁ is a focal length of the lens unit having positive optical power, and

f_(F) is a focal length of the focusing lens unit.

The condition (12) sets forth the focal length ratio between the focusing lens unit and the positive lens unit. When the value exceeds the upper limit of the condition (12), this indicates that the focal length of the focusing lens unit is excessively small. Thus, the image magnification change at the time of focusing becomes excessively large, and hence this situation is unpreferable. In contrast, when the value goes below the lower limit of the condition (12), this indicates that the focal length of the positive lens unit is excessively small. This causes an increase in aberration fluctuation at the time of zooming, and hence causes difficulty in compensation by other lens units.

Among the zoom lens systems according to the individual embodiments, in a case that the negative lens unit is arranged on the image side relative to the lens unit having positive optical power with the interval in between that varies at the time of zooming and that the focusing lens unit has negative optical power, it is preferable that the zoom lens system satisfies the following condition.

0.40<(r _(EF) −r _(IF))/(r _(EF) +r _(IF))<2.20   (13)

where,

r_(IF) is a radius of paraxial curvature of the most object side surface of the focusing lens unit, and

r_(EF) is a radius of paraxial curvature of the most image side surface of the focusing lens unit.

The condition (13) substantially sets forth the shape of the focusing lens unit. When the value goes outside the range of the condition (13), satisfactory compensation cannot be achieved for the off-axial aberration, especially, distortion. Thus, this situation is unpreferable.

Here, the individual lens units constituting each embodiment are composed exclusively of refractive type lens elements that deflect incident light by refraction (that is, lens elements of a type in which deflection is achieved at the interface between media each having a distinct refractive index). However, the present invention is not limited to this construction. For example, the lens units may employ diffractive type lens elements that deflect the incident light by diffraction; refractive-diffractive hybrid type lens elements that deflect the incident light by a combination of diffraction and refraction; or gradient index type lens elements that deflect the incident light by distribution of refractive index in the medium.

Embodiment 12

FIG. 45 is a block diagram of a camera system according to Embodiment 12. The camera system according to Embodiment 12 includes a camera body 100 and an interchangeable lens apparatus 200.

The camera body 100 includes a camera controller 101, an image sensor 102, a shutter unit 103, an image display controller 104, an image sensor control section 105, a contrast detection section 106, a shutter control section 107, an image recording control section 108, a display 110, a release button 111, a memory 112, a power supply 113 and a camera mount 114.

The camera controller 101 is an arithmetic operation unit for controlling the entire camera system. The camera controller 101 is electrically connected to the image display controller 104, the image sensor control section 105, the contrast detection section 106, the shutter control section 107, the image recording control section 108, the memory 112 and the camera mount 114, and can exchange signals with these sections. Further, the camera controller 101 is electrically connected to the release button 111, and receives a signal generated at the time of operation of the release button 111. Moreover, the camera controller 101 is connected to the power supply 113.

The image sensor 102 is composed, for example, of a CMOS sensor. The image sensor 102 converts an optical image incident on the light receiving plane into image data, and then outputs the image data. The image sensor 102 is driven in accordance with a driving signal from the image sensor control section 105. In response to a control signal from the camera controller 101, the image sensor control section 105 outputs a driving signal for driving the image sensor 102, and then outputs to the camera controller 101 the image data outputted from the image sensor 102. In response to a control signal from the camera controller 101, the contrast detection section 106 calculates and detects the contrast of the image data outputted from the image sensor 102, and then outputs the result to the camera controller 101.

The shutter unit 103 includes a shutter plate for shutting off the optical path for the image light to be incident on the image sensor 102. The shutter unit 103 is driven in accordance with a driving signal from the shutter control section 107. In response to a control signal from the camera controller 101, the shutter control section 107 controls the opening or closing timing for the shutter plate of the shutter unit 103.

The display 110 is composed, for example, of a liquid crystal display unit. The display 110 is driven in accordance with a driving signal from the image display controller 104 so as to display an image on the display surface. In response to a control signal from the camera controller 101, the image display controller 104 outputs image data to be displayed on the display 110 and a driving signal for driving the display 110.

In response to a control signal from the camera controller 101, the image recording control section 108 outputs image data to a memory card 109 connected in an attachable and removable manner.

The camera mount 114 mechanically connects the camera body 100 to the interchangeable lens apparatus 200 described later. Further, the camera mount 114 serves also as an interface for electrically connecting the camera body 100 to the interchangeable lens apparatus 200 described later.

The interchangeable lens apparatus 200 includes a lens controller 201, an image blur control section 202, a diaphragm control section 203, a focus control section 204, a zoom control section 205, a memory 206, a blur detection section 207, a diaphragm unit 208, a zoom lens system 209 (a zoom lens unit 209 a, a focusing lens unit 209 b and an image blur compensation lens unit 209 c), and a lens mount 210.

The lens controller 201 is an arithmetic operation unit for controlling the entirety of the interchangeable lens apparatus 200, and is connected through the lens mount 210 and the camera mount 114 to the camera controller 101 in the camera body described above. The lens controller 201 is electrically connected to the image blur control section 202, the diaphragm control section 203, the focus control section 204, the zoom control section 205, the memory 206 and the blur detection section 207, and can exchange signals with these sections.

The zoom lens system 209 is a zoom lens system according to Embodiment 1 described above. The zoom lens system 209 includes a zoom lens unit 209 a, a focusing lens unit 209 b, and an image blur compensation lens unit 209 c. Here, the classification of the zoom lens unit 209 a, the focusing lens unit 209 b and the image blur compensation lens unit 209 c is merely conceptual and adopted for simplicity of description. Thus, this classification does not exactly describe the actual construction of the actual zoom lens system. In the zoom lens system 209, zooming is achieved when the zoom lens unit 209 a moves in a direction along the optical axis. In the zoom lens system 209, focusing is achieved when the focusing lens unit 209 b moves in a direction along the optical axis. Further, in the zoom lens system 209, image blur compensation is achieved when the image blur compensation lens unit 209 c moves in a direction perpendicular to the optical axis.

In response to a control signal from the lens controller 201, the image blur control section 202 detects and outputs the present position of the image blur compensation lens unit 209 c. Further, the image blur control section 202 outputs a driving signal for driving the image blur compensation lens unit 209 c, so as to drive the image blur compensation lens unit 209 c in a direction perpendicular to the optical axis.

In response to a control signal from the lens controller 201, the diaphragm control section 203 detects and outputs the present position of the diaphragm unit 208. Further, the diaphragm control section 203 outputs a driving signal for driving the diaphragm blades provided in the diaphragm unit 208, and thereby opens or closes the diaphragm so as to change the F-number of the optical system.

In response to a control signal from the lens controller 201, the focus control section 204 detects and outputs the present position of the focusing lens unit 209 b. Further, the focus control section 204 outputs a driving signal for driving focusing group 209 b, so as to drive the focusing lens unit 209 b in a direction along the optical axis.

In response to a control signal from the lens controller 201, the zoom control section 205 detects and outputs the present position of the zoom lens unit 209 a. Further, the zoom control section 205 outputs a driving signal for driving the zoom lens unit 209 a, so as to drive the zoom lens unit 209 a in a direction along the optical axis.

In the above-mentioned configuration, when the release button 111 is pressed half, the camera controller 101 executes a routine of auto-focusing. First, the camera controller 101 communicates with the lens controller 201 via the camera mount 114 and the lens mount 210, so as to detect the state of the zoom lens unit 209 a, the focusing lens unit 209 b, the image blur compensation lens unit 209 c and the diaphragm unit 208.

Then, the camera controller 101 communicates with the lens controller 201 via the camera mount 114 and the lens mount 210, so as to output to the lens controller 201 a control signal for driving and wobbling the focusing lens unit 209 b. In accordance with the control signal, the lens controller 201 controls the focus control section 204 so as to drive and wobble the focusing lens unit 209 b. At the same time, the camera controller 101 communicates with the lens controller 201 via the camera mount 114 and the lens mount 210, so as to output a control signal for instructing the lens controller 201 to adjust the aperture value into a predetermined value. In accordance with the control signal, the lens controller 201 controls the diaphragm control section 203 so as to drive the diaphragm blades of the diaphragm unit 208 in correspondence to the predetermined F-number.

On the other hand, the camera controller 101 outputs a control signal to the image sensor control section 105 and the contrast detection section 106. The image sensor control section 105 and the contrast detection section 106 individually acquire an output from the image sensor 102 in a manner corresponding to the sampling frequency of the wobbling drive of the focusing lens unit 209 b. In accordance with the control signal from the camera controller 101, the image sensor control section 105 transmits image data corresponding to the optical image to the camera controller 101. The camera controller 101 performs predetermined image processing onto the image data, and then transmits the result to the image display controller 104. The image display controller 104 displays the image data in the form of a visible image onto the display 110.

Further, the contrast detection section 106 calculates the contrast value of the image data in association with wobbling, and then transmits the result to the camera controller 101. On the basis of the detection result from the contrast detection section 106, the camera controller 101 determines the direction of focusing movement and the amount of movement for the focusing lens unit, and then transmits the information thereof to the lens controller 201. The lens controller 201 outputs a control signal to the focus control section 204 so as to move the focusing lens unit 209 b. In accordance with the control signal from the lens controller 201, the focus control section 204 drives the focusing lens unit 209 b.

When auto-focusing is to be performed in a live view state, the above-mentioned operation is repeated. When auto-focusing is to be performed in a live view state, wobbling of the focusing lens unit 209 b is performed continuously. At that time, the zoom lens system according to each embodiment has merely a small image magnification change in association with wobbling, and has a light weight. Thus, an imaging lens system suitable for the above-mentioned system is obtained.

Embodiment 12 given above has been described for a case that the zoom lens system according to Embodiment 1 is employed. However, obviously, a zoom lens system according to another embodiment may be employed. Here, among the zoom lens systems according to the embodiments, when a zoom lens system that does not include the image blur compensation lens unit 209 c is employed, the configuration of the image blur control section 202 and the like is omitted.

Examples

Numerical examples are described below in which the zoom lens systems according to Embodiments 1 to 11 are implemented. As described later, Numerical Examples 1 to 11 correspond to Embodiments 1 to 11, respectively. In the numerical examples, the units of the length in the tables are all “mm”, while the units of the view angle are all “°”. Moreover, in the numerical examples, r is the radius of curvature, d is the axial distance, nd is the refractive index to the d-line, and vd is the Abbe number to the d-line. In the numerical examples, the surfaces marked with * are aspheric surfaces, and the aspheric surface configuration is defined by the following expression.

$Z = {\frac{h^{2}/r}{1 + \sqrt{1 - {\left( {1 + \kappa} \right)\left( {k/r} \right)^{2}}}} + {\sum{A_{n}h^{n}}}}$

Here, the symbols in the formula indicate the following quantities.

Z is the distance from a point on an aspheric surface at a height h relative to the optical axis to a tangential plane at the vertex of the aspheric surface,

h is the height relative to the optical axis,

r is the radius of curvature at the top,

κ is the conic constant, and

An is the n-th order aspherical coefficient.

FIGS. 2, 6, 10, 14, 18, 22, 26, 30, 34, 38 and 42 are longitudinal aberration diagrams of an infinity in-focus condition of the zoom lens systems according to Numerical Examples 1, 2, 3, 4, 5, 6, 7, 8, 9, 10 and 11, respectively.

FIGS. 3, 7, 11, 15, 19, 23, 27, 31, 35, 39 and 43 are longitudinal aberration diagrams of a close-point in-focus condition of the zoom lens systems according to Numerical Examples 1, 2, 3, 4, 5, 6, 7, 8, 9, 10 and 11, respectively.

In each longitudinal aberration diagram, part (a) shows the aberration at a wide-angle limit, part (b) shows the aberration at a middle position, and part (c) shows the aberration at a telephoto limit. Each longitudinal aberration diagram, in order from the left-hand side, shows the spherical aberration (SA (mm)), the astigmatism (AST (mm)) and the distortion (DIS (%)). In each spherical aberration diagram, the vertical axis indicates the F-number (in each Fig., indicated as F), and the solid line, the short dash line and the long dash line indicate the characteristics to the d-line, the F-line and the C-line, respectively. In each astigmatism diagram, the vertical axis indicates the image height (in each Fig., indicated as H), and the solid line and the dash line indicate the characteristics to the sagittal image plane (in each Fig., indicated as “s”) and the meridional image plane (in each Fig., indicated as “m”), respectively. In each distortion diagram, the vertical axis indicates the image height (in each Fig., indicated as H).

In each numerical example, as seen from the longitudinal aberration diagram of an infinity in-focus condition and the longitudinal aberration diagram of a close-point in-focus condition, also in a close-point in-focus condition, each zoom lens system achieves satisfactory aberration performance similar to that in an infinity in-focus condition.

FIGS. 4, 8, 12, 16, 20, 24, 28, 32, 36, 40 and 44 are lateral aberration diagrams in a basic state where image blur compensation is not performed and in an image blur compensation state of a zoom lens system according to Numerical Examples 1, 2, 3, 4, 5, 6, 7, 8, 9, 10 and 11, respectively.

In each lateral aberration diagram, the aberration diagrams in the upper three parts correspond to a basic state where image blur compensation is not performed at a telephoto limit, while the aberration diagrams in the lower three parts correspond to an image blur compensation state where the entire second lens unit G2 moves by a predetermined amount in a direction perpendicular to the optical axis at a telephoto limit. Among the lateral aberration diagrams of a basic state, the upper part shows the lateral aberration at an image point of 75% of the maximum image height, the middle part shows the lateral aberration at the axial image point, and the lower part shows the lateral aberration at an image point of −75% of the maximum image height. Among the lateral aberration diagrams of an image blur compensation state, the upper part shows the lateral aberration at an image point of 75% of the maximum image height, the middle part shows the lateral aberration at the axial image point, and the lower part shows the lateral aberration at an image point of −75% of the maximum image height. In each lateral aberration diagram, the horizontal axis indicates the distance from the principal ray on the pupil surface, and the solid line, the short dash line and the long dash line indicate the characteristics to the d-line, the F-line and the C-line, respectively. In each lateral aberration diagram, the meridional image plane is adopted as the plane containing the optical axis of the first lens unit G1.

Here, in the zoom lens system according to each numerical example, the amount (Y_(T)) of movement of the compensation lens unit in a direction perpendicular to the optical axis in an image blur compensation state at a telephoto limit is as follows.

TABLE 1 (amount of movement of compensation lens unit) Numerical Example Y_(T) 1 0.150 2 0.170 3 0.290 4 0.300 5 0.320 6 0.400 7 0.280 8 0.320 9 0.450 10 0.500 11 0.470

As seen from the lateral aberration diagrams, in each zoom lens system, satisfactory symmetry is obtained in the lateral aberration at the axial image point. Further, when the lateral aberration at the +75% image point and the lateral aberration at the −75% image point are compared with each other in a basic state, all have a small degree of curvature and almost the same inclination in the aberration curve. Thus, decentering coma aberration and decentering astigmatism are small. This indicates that satisfactory imaging performance is obtained even in an image blur compensation state. Further, when the image blur compensation angle of a zoom lens system is the same, the amount of parallel translation required for image blur compensation decreases with decreasing focal length of the entire zoom lens system. Thus, at arbitrary zoom positions, satisfactory image blur compensation can be performed without degrading the imaging characteristics.

Numerical Example 1

The zoom lens system of Numerical Example 1 corresponds to Embodiment 1 shown in FIG. 1. Table 2 shows the surface data of the zoom lens system of Numerical Example 1. Table 3 shows the aspherical data. Table 4 shows various data. Table 5 shows the zoom lens unit data.

TABLE 2 (surface data) Surface number r D nd vd Object surface ∞  1 43.21710 1.20000 1.84666 23.8  2 25.43470 5.19210 1.80420 46.5  3 981.95530 Variable  4 82.59040 0.70000 1.88300 40.8  5 9.38020 4.75790  6 −35.73240 0.70000 1.80420 46.5  7 44.32840 0.15000  8 18.94040 3.04020 1.84666 23.8  9 −49.21050 Variable 10 −19.76000 0.80000 1.80420 46.5 11 −138.28540 Variable 12 41.91760 2.27020 1.48749 70.4 13* −18.78750 3.00000 14 (Aperture) ∞ 0.80000 15 11.80590 9.59870 1.48749 70.4 16 −9.25040 0.80000 1.80991 41.0 17 −19.17090 0.10000 18 22.73290 0.80000 1.84330 24.7 19 9.42400 8.93080 20 21.02660 2.03030 1.78220 25.7 21 41.29530 BF Image surface ∞

TABLE 3 (aspherical data) Surface No. Parameters 13 K = −2.22931E−01, A4 = 3.37806E−05, A6 = 7.70077E−07, A8 = −4.63479E−08, A10 = 7.39065E−10

TABLE 4 (various data) Zooming ratio 3.05147 Wide Middle Telephoto Focal length 14.4088 25.1686 43.9679 F-number 3.60905 4.84348 5.99491 View angle 40.3126 23.7421 13.6890 Image height 11.0000 11.0000 11.0000 Overall length of 77.1851 86.0327 102.2025 lens system BF 15.84139 25.45859 36.32682 d3 0.5000 6.5616 14.9075 d9 4.4250 2.5240 2.9980 d11 11.5485 6.6183 3.1000

TABLE 5 (zoom lens unit data) Unit Initial surface No. Focal length 1 1 58.21940 2 4 −20.78405 3 10 −28.75388 4 12 17.86944

Numerical Example 2

The zoom lens system of Numerical Example 2 corresponds to Embodiment 2 shown in FIG. 5. Table 6 shows the surface data of the zoom lens system of Numerical Example 2. Table 7 shows the aspherical data. Table 8 shows various data. Table 9 shows the zoom lens unit data.

TABLE 6 (surface data) Surface number r d nd vd Object surface ∞  1 33.83330 1.20000 1.84666 23.8  2 20.77060 0.01000 1.56732 42.8  3 20.77060 6.28590 1.80420 46.5  4 116.39280 Variable  5 38.71660 0.70000 1.88300 40.8  6 8.80740 4.80720  7 −44.40300 0.70000 1.80420 46.5  8 23.11540 0.15000  9 15.40440 3.15370 1.84666 23.8 10 −49.21050 Variable 11 −18.01480 0.80000 1.80420 46.5 12 −132.85380 Variable 13 48.60620 2.03210 1.51443 63.3 14* −18.57800 3.00000 15 (Aperture) ∞ 0.80000 16 9.81310 2.84000 1.49475 69.6 17 −36.80060 0.01000 1.56732 42.8 18 −36.80060 0.96930 1.76995 27.6 19 29.16220 9.46760 20 84.07330 2.08380 1.48749 70.4 21 −20.12000 1.68460 22 −8.42020 0.80000 1.75221 51.7 23 −15.68550 0.15000 24 26.62400 2.39610 1.54929 46.8 25 6476.67870 BF Image surface ∞

TABLE 7 (aspherical data) Surface No. Parameters 14 K = 6.62676E−02, A4 = 2.73404E−05, A6 = 2.59552E−08, A8 = 6.74138E−10, A10 = −1.11287E−11

TABLE 8 (various data) Zooming ratio 3.05357 Wide Middle Telephoto Focal length 14.4000 25.1643 43.9713 F-number 3.60956 4.87199 5.49083 View angle 40.5373 24.6639 14.1615 Image height 11.0000 11.0000 11.0000 Overall length of 72.6963 80.8343 97.7212 lens system BF 15.17359 27.31874 33.30463 d4 0.5000 2.8614 15.6225 d10 2.5839 2.3994 3.1538 d12 10.3985 4.2145 1.6000

TABLE 9 (zoom lens unit data) Unit Initial surface No. Focal length 1 1 59.63024 2 5 −22.12178 3 11 −25.99565 4 13 17.09235

Numerical Example 3

The zoom lens system of Numerical Example 3 corresponds to Embodiment 3 shown in FIG. 9. Table 10 shows the surface data of the zoom lens system of Numerical Example 3. Table 11 shows the aspherical data. Table 12 shows various data. Table 13 shows the zoom lens unit data.

TABLE 10 (surface data) Surface number r d nd vd Object surface ∞  1 33.75060 1.20000 1.84666 23.8  2 20.77890 0.01000 1.56732 42.8  3 20.77890 6.15900 1.80420 46.5  4 120.41460 Variable  5 37.60080 0.70000 1.88300 40.8  6 8.72600 4.70880  7 −55.82480 0.70000 1.80420 46.5  8 20.72170 0.15000  9 14.41540 3.22770 1.84666 23.8 10 −49.21050 Variable 11 −17.47170 0.80000 1.80420 46.5 12 −253.90150 Variable 13 −169.66660 1.52820 1.72916 54.7 14 −27.83260 3.00000 15 (Aperture) ∞ 0.80000 16 11.11030 3.20560 1.61016 60.9 17 −17.84460 0.01000 1.56732 42.8 18 −17.84460 0.91610 1.83802 26.3 19 −678.72260 8.21640 20* 29.09570 2.26450 1.48749 70.4 21 −15.62460 0.85280 22 −9.25560 0.80000 1.80477 45.9 23 93.92590 1.82920 24 30.39700 3.27490 1.58369 40.0 25 −26.56500 BF Image surface ∞

TABLE 11 (aspherical data) Surface No. Parameters 20 K = 0.00000E+00, A4 = −9.31373E−05, A6 = −8.61821E−07, A8 = 1.81544E−08, A10 = −1.10493E−09

TABLE 12 (various data) Zooming ratio 3.05267 Wide Middle Telephoto Focal length 14.4045 25.1613 43.9722 F-number 3.60886 4.78574 5.43549 View angle 40.5307 24.4885 14.0613 Image height 11.0000 11.0000 11.0000 Overall length of 72.7053 81.3086 97.7139 lens system BF 15.17729 26.86964 33.35743 d4 0.5000 3.4867 15.3708 d10 2.4989 2.3529 3.0325 d12 10.1759 4.2462 1.6000

TABLE 13 (zoom lens unit data) Unit Initial surface No. Focal length 1 1 58.71443 2 5 −24.41553 3 11 −23.36629 4 13 16.94894

Numerical Example 4

The zoom lens system of Numerical Example 4 corresponds to Embodiment 4 shown in FIG. 13. Table 14 shows the surface data of the zoom lens system of Numerical Example 4. Table 15 shows the aspherical data. Table 16 shows various data. Table 17 shows the zoom lens unit data.

TABLE 14 (surface data) Surface number r d nd vd Object surface ∞  1 41.58720 1.20000 1.84666 23.8  2 24.98410 0.01000 1.56732 42.8  3 24.98410 7.27960 1.80420 46.5  4 148.93230 Variable  5 44.23380 0.70000 1.90366 31.3  6 9.20050 4.94480  7 −35.03150 0.70000 1.80420 46.5  8 22.98100 0.18430  9 17.02960 3.41510 1.92286 20.9 10 −37.71140 Variable 11 −20.25230 0.70000 1.82386 32.0 12 −105.30170 Variable 13 −196.54500 1.44540 1.80420 46.5 14 −38.60810 1.10000 15 18.40860 2.93490 1.74400 44.9 16 −14.22720 0.01000 1.56732 42.8 17 −14.22720 0.81380 1.84666 23.8 18 −161.45670 1.10000 19 (Aperture) ∞ 13.89740 20* 33.37530 3.56480 1.51443 63.3 21 −10.14430 0.01000 1.56732 42.8 22 −10.14430 0.70000 1.80610 33.3 23 75.47740 0.50910 24 27.51340 2.37520 1.84666 23.8 25 −500.00000 BF Image surface ∞

TABLE 15 (aspherical data) Surface No. Parameters 20 K = 0.00000E+00, A4 = −4.64962E−05, A6 = −1.26354E−07, A8 = 7.29053E−09, A10 = −1.62407E−10

TABLE 16 (various data) Zooming ratio 3.03421 Wide Middle Telephoto Focal length 14.4002 25.0830 43.6932 F-number 3.62531 4.79832 5.66523 View angle 40.4543 24.6084 14.1553 Image height 11.0000 11.0000 11.0000 Overall length of 77.7025 85.6771 105.7196 lens system BF 15.06999 26.58189 32.15024 d4 0.5400 4.3311 20.6494 d10 3.1685 2.6924 3.7256 d12 11.3296 4.4773 1.6000

TABLE 17 (zoom lens unit data) Unit Initial surface No. Focal length 1 1 72.67423 2 5 −24.38947 3 11 −30.54929 4 13 18.36280

Numerical Example 5

The zoom lens system of Numerical Example 5 corresponds to Embodiment 5 shown in FIG. 17. Table 18 shows the surface data of the zoom lens system of Numerical Example 5. Table 19 shows the aspherical data. Table 20 shows various data. Table 21 shows the zoom lens unit data.

TABLE 18 (surface data) Surface number r d nd vd Object surface ∞  1 42.96070 1.20000 1.84666 23.8  2 25.92060 0.01000 1.56732 42.8  3 25.92060 6.55090 1.80420 46.5  4 169.01970 Variable  5 48.51820 0.70000 1.90366 31.3  6 9.29630 4.91560  7 −35.68210 0.70000 1.80420 46.5  8 24.70060 0.29410  9 18.12650 3.49270 1.92286 20.9 10 −42.04300 Variable 11 −24.12750 0.70000 1.80610 33.3 12 −126.46290 Variable 13 −199.24170 1.43970 1.80420 46.5 14 −41.67830 1.10000 15 16.18500 3.04630 1.78590 43.9 16 −15.20920 0.01000 1.56732 42.8 17 −15.20920 0.71710 1.84666 23.8 18 190.44830 1.15620 19 (Aperture) ∞ 10.81490 20* 104.94440 3.00310 1.51443 63.3 21 −8.88270 0.01000 1.56732 42.8 22 −8.88270 0.70000 1.80420 46.5 23 −78.31910 3.20510 24 26.91780 2.38950 1.54814 45.8 25 −500.00000 BF Image surface ∞

TABLE 19 (aspherical data) Surface No. Parameters 20 K = 0.00000E+00, A4 = −6.89162E−05, A6 = −1.16507E−07, A8 = −1.02112E−08, A10 = 3.91677E−11

TABLE 20 (various data) Zooming ratio 3.01481 Wide Middle Telephoto Focal length 14.4010 25.0043 43.4164 F-number 3.62104 5.03037 5.66149 View angle 40.4482 24.5894 14.1746 Image height 11.0000 11.0000 11.0000 Overall length of 77.5984 85.4062 105.7130 lens system BF 15.06783 26.51298 32.51998 d4 0.6229 4.6469 20.7822 d10 3.4652 3.1732 4.6556 d12 12.2873 4.9179 1.6000

TABLE 21 (zoom lens unit data) Unit Initial surface No. Focal length 1 1 72.96184 2 5 −22.11132 3 11 −37.10127 4 13 19.15115

Numerical Example 6

The zoom lens system of Numerical Example 6 corresponds to Embodiment 6 shown in FIG. 21. Table 22 shows the surface data of the zoom lens system of Numerical Example 6. Table 23 shows the aspherical data. Table 24 shows various data. Table 25 shows the zoom lens unit data.

TABLE 22 (surface data) Surface number r d nd vd Object surface ∞  1 42.07080 1.20000 1.84666 23.8  2 25.79060 0.01000 1.56732 42.8  3 25.79060 7.28790 1.80420 46.5  4 149.71930 Variable  5 53.82100 0.70000 1.90366 31.3  6 9.38730 4.85820  7 −37.12600 1.20000 1.80470 41.0  8* 32.30060 1.13550  9 21.79130 3.07180 1.92286 20.9 10 −42.23590 Variable 11 −35.48460 0.70000 1.80610 33.3 12 145.22990 Variable 13 150.96840 1.40280 1.80420 46.5 14 −112.84260 1.10000 15 12.62530 3.20010 1.74330 49.2 16 −21.40160 0.01000 1.56732 42.8 17 −21.40160 0.92210 1.84666 23.8 18 149.23410 1.27460 19 (Aperture) ∞ 6.54640 20* 29.12070 2.50410 1.51443 63.3 21 −7.46520 0.01000 1.56732 42.8 22 −7.46520 0.70000 1.80420 46.5 23 48.76610 5.51350 24 26.79300 2.94610 1.48749 70.4 25 −43.27020 BF Image surface ∞

TABLE 23 (aspherical data) Surface No. Parameters 8 K = 0.00000E+00, A4 = −6.79186E−06, A6 = 2.75874E−07, A8 = −8.27389E−09, A10 = 6.56929E−11 20 K = 0.00000E+00, A4 = −1.25292E−04, A6 = −3.82479E−06, A8 = 3.46565E−07, A10 = −1.23309E−08

TABLE 24 (various data) Zooming ratio 3.02778 Wide Middle Telephoto Focal length 14.4201 25.0932 43.6607 F-number 3.58227 4.87586 5.83037 View angle 40.4947 24.4473 14.1473 Image height 11.0000 11.0000 11.0000 Overall length of 77.5939 86.5453 105.7177 lens system BF 15.06249 25.57110 31.85013 d4 0.4000 6.3000 21.4205 d10 3.3746 3.2765 4.5540 d12 12.4637 5.1046 1.6000

TABLE 25 (zoom lens unit data) Unit Initial surface No. Focal length 1 1 73.53054 2 5 −25.93488 3 11 −35.31538 4 13 19.55654

Numerical Example 7

The zoom lens system of Numerical Example 7 corresponds to Embodiment 7 shown in FIG. 25. Table 26 shows the surface data of the zoom lens system of Numerical Example 7. Table 27 shows the aspherical data. Table 28 shows various data. Table 29 shows the zoom lens unit data.

TABLE 26 (surface data) Surface number r d nd vd Object surface ∞  1 97.18260 1.20000 1.84666 23.8  2 59.22040 5.64620 1.49700 81.6  3 623.98800 0.20000  4 64.74630 4.11060 1.72916 54.7  5 257.04630 Variable  6 44.95400 1.00000 1.88300 40.8  7 14.89470 6.11710  8 −65.21500 0.80000 1.83481 42.7  9 79.27340 0.30000 10 27.37660 2.66150 1.92286 18.9 11 975.15220 Variable 12 −25.99020 0.70000 1.83481 42.7 13 25.72820 0.30000 14 24.64350 1.58960 1.84666 23.8 15 83.01740 Variable 16 (Aperture) ∞ 1.17000 17 27.09090 1.74340 1.62299 58.1 18 −241.48760 0.30000 19* 12.93580 1.93840 1.48749 70.4 20 33.46510 0.30000 21 28.94950 0.70000 1.83400 37.3 22 14.51370 Variable 23 13.46950 3.82840 1.84666 23.8 24 8.75400 3.67160 1.51760 63.5 25* −42.54940 1.00000 26 −113.24540 0.70000 1.84666 23.8 27 37.31110 5.96160 28* 27.61410 4.00480 1.68893 31.1 29 −18.37350 1.65420 30 −12.35470 0.70000 1.83481 42.7 31 −66.88770 BF Image surface ∞

TABLE 27 (aspherical data) Surface No. Parameters 19 K = 0.00000E+00, A4 = −2.54373E−05, A6 = −4.36871E−09, A8 = −1.59208E−09, A10 = 0.00000E+00 25 K = 0.00000E+00, A4 = 5.90621E−05, A6 = 1.10756E−07, A8 = −7.79429E−09, A10 = 8.72488E−11 28 K = 0.00000E+00, A4 = 2.57689E−05, A6 = 8.95676E−08, A8 = 8.00095E−10, A10 = 2.23671E−11

TABLE 28 (various data) Zooming ratio 10.01328 Wide Middle Telephoto Focal length 14.4802 47.0012 144.9939 F-number 4.10714 6.08617 6.29290 View angle 40.3350 13.0043 4.2787 Image height 11.0000 11.0000 11.0000 Overall length of 101.5678 132.1204 165.0546 lens system BF 16.86766 34.71640 47.67448 d5 0.3000 28.6184 53.5827 d11 5.0309 4.6988 7.5000 d15 20.1091 8.5806 2.0000 d22 6.9627 3.2088 2.0000

TABLE 29 (zoom lens unit data) Unit Initial surface No. Focal length 1 1 95.87909 2 6 −38.06367 3 12 −24.81420 4 16 38.91764 5 23 35.37675

Numerical Example 8

The zoom lens system of Numerical Example 8 corresponds to Embodiment 8 shown in FIG. 29. Table 30 shows the surface data of the zoom lens system of Numerical Example 8. Table 31 shows the aspherical data. Table 32 shows various data. Table 33 shows the zoom lens unit data.

TABLE 30 (surface data) Surface number r d nd vd Object surface ∞  1 72.06380 1.20000 1.84666 23.8  2 44.82460 4.94400 1.49700 81.6  3 179.32400 0.20000  4 56.21680 3.99930 1.77250 49.6  5 235.44770 Variable  6 40.85450 1.00000 1.90366 31.3  7 12.04170 5.66070  8 −46.87750 0.70000 1.80610 33.3  9 49.74080 0.20000 10 22.47680 3.63460 1.94595 18.0 11 −94.62740 Variable 12 −23.49900 0.70000 1.80420 46.5 13 −836.21030 Variable 14 (Aperture) ∞ 1.17000 15 17.38230 2.43350 1.69400 56.3 16* −68.55390 0.30000 17 12.85750 3.27960 1.61800 63.4 18 −39.58700 0.01000 1.56732 42.8 19 −39.58700 1.98900 1.80610 33.3 20 10.06630 0.96040 21 31.38760 2.27190 1.48749 70.4 22 −19.38890 1.05190 23 −531.47260 1.91500 1.84666 23.8 24 −12.13420 0.70000 1.80610 33.3 25 18.75770 Variable 26 −86.82700 1.78870 1.51760 63.5 27* −15.68550 1.84310 28 −10.98090 0.70000 1.80420 46.5 29 −22.08400 0.20000 30 26.94980 4.22470 1.51742 52.1 31 −12.32080 0.01000 1.56732 42.8 32 −12.32080 0.70000 1.80420 46.5 33 −27.27430 BF Image surface ∞

TABLE 31 (aspherical data) Surface No. Parameters 16 K = 0.00000E+00, A4 = 4.31647E−05, A6 = −1.18892E−07, A8 = 1.91929E−09, A10 = −1.91817E−11, A12 = 0.00000E+00 27 K = 0.00000E+00, A4 = −4.60035E−05, A6 = −2.87752E−07, A8 = −6.89809E−09, A10 = −8.47311E−11, A12 = 6.07866E−13

TABLE 32 (various data) Zooming ratio 8.31912 Wide Middle Telephoto Focal length 14.5000 45.7985 120.6276 F-number 4.12045 4.96080 5.80028 View angle 40.3065 13.5211 5.2219 Image height 11.0000 11.0000 11.0000 Overall length of 93.5691 119.5950 148.5703 lens system BF 14.95014 33.17625 43.27012 d5 0.6000 22.5177 43.8164 d11 2.9000 3.8000 7.1000 d13 24.5466 9.4198 2.1700 d25 2.7860 2.8949 4.4274

TABLE 33 (zoom lens unit data) Unit Initial surface No. Focal length 1 1 85.89197 2 6 −39.48361 3 12 −30.07678 4 14 21.41574 5 26 57.67340

Numerical Example 9

The zoom lens system of Numerical Example 9 corresponds to Embodiment 9 shown in FIG. 33. Table 34 shows the surface data of the zoom lens system of Numerical Example 9. Table 35 shows the aspherical data. Table 36 shows various data. Table 37 shows the zoom lens unit data.

TABLE 34 (surface data) Surface number r d nd vd Object surface ∞  1 35.57350 1.20000 1.84666 23.8  2 24.39090 0.01000 1.56732 42.8  3 24.39090 8.21250 1.72916 54.7  4 112.49750 Variable  5 29.46230 0.70000 1.88300 40.8  6 8.55300 3.90780  7 49.08160 0.70000 1.80420 46.5  8 14.90170 0.15020  9 11.22820 2.66860 1.88627 20.9 10 38.17570 Variable 11 −21.57740 0.80000 1.80420 46.5 12 −208.58690 Variable 13 (Aperture) ∞ 0.80000 14 38.62380 2.55330 1.65741 58.1 15 −8.46830 0.01000 1.56732 42.8 16 −8.46830 0.70000 1.81573 36.6 17 −20.64780 2.00000 18 −49.37020 0.80000 1.72916 54.7 19 −275.28120 Variable 20* 72.15450 2.17600 1.73185 54.3 21 −31.32140 0.15010 22 16.93800 4.32260 1.48749 70.4 23 −23.22450 0.10000 24 56.11280 0.80000 1.81730 35.6 25 12.18130 BF Image surface ∞

TABLE 35 (aspherical data) Surface No. Parameters 20 K = 0.00000E+00, A4 = −6.87649E−05, A6 = 1.14968E−07, A8 = −4.14869E−09

TABLE 36 (various data) Zooming ratio 3.05354 Wide Middle Telephoto Focal length 14.3999 25.1622 43.9705 F-number 3.60603 4.55238 5.32062 View angle 40.5114 23.8476 13.7742 Image height 11.0000 11.0000 11.0000 Overall length of 77.6987 87.6960 102.4577 lens system BF 25.09499 31.53207 38.41726 d4 0.5000 11.2352 22.4826 d10 3.2373 3.3918 4.1968 d12 10.9135 6.1013 2.5999 d19 5.1918 2.6745 2.0000

TABLE 37 (zoom lens unit data) Unit Initial surface No. Focal length 1 1 75.39944 2 5 −20.57322 3 11 −29.98384 4 13 37.91877 5 20 25.50754

Numerical Example 10

The zoom lens system of Numerical Example 10 corresponds to Embodiment 10 shown in FIG. 37. Table 38 shows the surface data of the zoom lens system of Numerical Example 10. Table 39 shows the aspherical data. Table 40 shows various data. Table 41 shows the zoom lens unit data.

TABLE 38 (surface data) Surface number r d nd vd Object surface ∞  1 39.75020 1.20000 1.84666 23.8  2 23.31650 0.01000 1.56732 42.8  3 23.31650 7.53790 1.80420 46.5  4 167.75010 Variable  5 42.91510 0.70000 1.88300 40.8  6 9.03750 4.49980  7 −75.23540 0.70000 1.80420 46.5  8 22.01970 0.15000  9 14.96860 3.06300 1.84666 23.8 10 −72.10310 Variable 11 −19.97180 0.80000 1.80420 46.5 12 −130.61870 Variable 13 (Aperture) ∞ 0.80000 14 −106.10960 1.34960 1.80420 46.5 15 −42.01180 0.15000 16 14.23240 3.02120 1.73636 53.7 17 −15.89850 0.01000 1.56732 42.8 18 −15.89850 0.86370 1.82815 30.0 19 140.77420 6.45490 20 50.63850 0.80000 1.62041 60.3 21 25.63810 2.11440 22* 16.88120 4.95270 1.51443 63.3 23 −8.03600 0.01000 1.56732 42.8 24 −8.03600 0.80000 1.77823 48.9 25 −32.94730 BF Image surface ∞

TABLE 39 (aspherical data) Surface No. Parameters 22 K = 2.89522E+00, A4 = −1.28550E−04, A6 = −1.62009E−07, A8 = −5.76957E−09, A10 = 2.55610E−11

TABLE 40 (various data) Zooming ratio 3.05354 Wide Middle Telephoto Focal length 14.4000 25.1644 43.9710 F-number 3.60857 4.53853 5.34109 View angle 40.4086 23.7802 13.7807 Image height 11.0000 11.0000 11.0000 Overall length of 76.6965 86.7484 101.6734 lens system BF 20.86496 28.17383 36.35448 d4 0.5000 9.2699 18.8608 d10 3.4709 2.7585 3.8709 d12 11.8734 6.5590 2.6000

TABLE 41 (zoom lens unit data) Unit Initial surface No. Focal length 1 1 65.93589 2 5 −22.50678 3 11 −29.41177 4 13 17.42374

Numerical Example 11

The zoom lens system of Numerical Example 11 corresponds to Embodiment 11 shown in FIG. 41. Table 42 shows the surface data of the zoom lens system of Numerical Example 11. Table 43 shows the aspherical data. Table 44 shows various data. Table 45 shows the zoom lens unit data.

TABLE 42 (surface data) Surface number r d nd vd Object surface ∞  1 54.67070 1.20000 1.84666 23.8  2 29.73640 0.01000 1.56732 42.8  3 29.73640 5.69850 1.80420 46.5  4 366.83850 Variable  5 47.76190 0.70000 1.88300 40.8  6 9.80640 4.42270  7 −66.68270 0.70000 1.80420 46.5  8 26.99710 0.15000  9 16.93620 3.04290 1.84666 23.8 10 −71.10620 Variable 11 −21.70620 0.80000 1.80420 46.5 12 −77.48440 Variable 13 (Aperture) ∞ 0.80000 14 −641.22280 1.47800 1.80420 46.5 15 −37.85060 0.15000 16 15.49410 2.79940 1.74330 49.2 17 −23.08580 0.01000 1.56732 42.8 18 −23.08580 3.30070 1.80518 25.5 19 48.95390 4.75370 20 209.66310 0.80000 1.51680 64.2 21 35.68140 5.06070 22* 16.93910 5.60780 1.51443 63.3 23 −8.63840 0.01000 1.56732 42.8 24 −8.63840 0.80000 1.74330 49.2 25 −56.39880 BF Image surface ∞

TABLE 43 (aspherical data) Surface No. Parameters 22 K = 2.91946E+00, A4 = −1.15818E−04, A6 = −3.30944E−07, A8 = −5.69984E−10, A10 = −9.08042E−11

TABLE 44 (various data) Zooming ratio 3.05357 Wide Middle Telephoto Focal length 14.4015 25.1650 43.9760 F-number 3.60574 4.61537 5.61571 View angle 40.4525 23.6345 13.7790 Image height 11.0000 11.0000 11.0000 Overall length of 78.5958 89.5418 106.5805 lens system BF 17.56606 25.56657 35.56770 d4 1.1532 11.2057 22.2817 d10 3.4367 3.1363 3.8367 d12 14.1454 7.3388 2.6000

TABLE 45 (zoom lens unit data) Unit Initial surface No. Focal length 1 1 83.33335 2 5 −24.19692 3 11 −37.73591 4 13 18.61647

The following Tables 46 to 48 show values corresponding to the individual conditions in the zoom lens systems of the numerical examples.

TABLE 46 (values corresponding to individual conditions: Numerical Examples 1 to 4) Numerical Example Conditions 1 2 3 4 (1) |f_(F)/f_(W)| 1.99561 1.80526 1.62215 2.12143 (2) |f_(F)/f_(T)| 0.65399 0.59120 0.53138 0.69917 (3) |f_(F)/f_(NW)| 3.17346 2.83286 2.58857 2.96526 (4) β_(NT)/β_(NW) 1.53665 1.55566 1.55763 1.59346 (5) D_(F)/ΣD 0.01783 0.01817 0.01804 0.01471 (6) |f₁/f_(NW)| 6.42549 6.49814 6.50453 7.05410 (7) D_(FWA)/f_(W) 1.16728 1.07160 1.02080 1.30093 (8) (D_(F)/f_(W)) * (f_(T)/f_(W)) 0.16943 0.16964 0.16954 0.14749 (9) |D_(F)/f_(F)| 0.02782 0.03077 0.03424 0.02291 (10) |f₁/f₂| 2.80116 2.69553 2.40477 2.97976 (11) |f₂/f_(F)| 0.72283 0.85098 1.04492 0.79836 (12) |f₁/f_(F)| 2.02475 2.29385 2.51279 2.37892 (13) (r_(EF) − r_(IF))/(r_(EF) + r_(IF)) 0.74995 0.76119 0.87123 0.67739

TABLE 47 (values corresponding to individual conditions: Numerical Examples 5 to 8) Numerical Example Conditions 5 6 7 8 (1) |f_(F)/f_(W)| 2.57629 2.44906 1.71365 2.07425 (2) |f_(F)/f_(T)| 0.85455 0.80886 0.17114 0.24934 (3) |f_(F)/f_(NW)| 3.44090 3.23073 2.09418 2.23928 (4) β_(NT)/β_(NW) 1.57193 1.61106 3.66975 3.07933 (5) D_(F)/ΣD 0.01517 0.01512 0.05065 0.01502 (6) |f₁/f_(NW)| 6.76675 6.72672 8.09168 6.39482 (7) D_(FWA)/f_(W) 1.37189 1.41285 1.38873 1.69286 (8) (D_(F)/f_(W)) * (f_(T)/f_(W)) 0.14654 0.14698 1.79075 0.40161 (9) |D_(F)/f_(F)| 0.01887 0.01982 0.10436 0.02327 (10) |f₁/f₂| 3.29975 2.83522 2.51892 2.17540 (11) |f₂/f_(F)| 0.59597 0.73437 1.53394 1.31274 (12) |f₁/f_(F)| 1.96656 2.08211 3.86388 2.85575 (13) (r_(EF) − r_(IF))/(r_(EF) + r_(IF)) 0.67956 1.59766 1.91150 0.94533

TABLE 48 (values corresponding to individual conditions: Numerical Examples 9 to 11) Numerical Example Conditions 9 10 11 (1) |f_(F)/f_(W)| 2.08223 2.04249 2.62029 (2) |f_(F)/f_(T)| 0.68191 0.66888 0.85810 (3) |f_(F)/f_(NW)| 2.94598 2.95261 3.15057 (4) β_(NT)/β_(NW) 1.66984 1.63688 1.48882 (5) D_(F)/ΣD 0.02276 0.02041 0.01928 (6) |f₁/f_(NW)| 7.40813 6.61920 6.95749 (7) D_(FWA)/f_(W) 0.75789 0.82454 0.98223 (8) (D_(F)/f_(W)) * (f_(T)/f_(W)) 0.16964 0.16964 0.16963 (9) |D_(F)/f_(F)| 0.02668 0.02720 0.02120 (10) |f₁/f₂| 3.66489 2.92961 3.44397 (11) |f₂/f_(F)| 0.68615 0.76523 0.64122 (12) |f₁/f_(F)| 2.51466 2.24181 2.20833 (13) (r_(EF) − r_(IF))/(r_(EF) + r_(IF)) 0.81250 0.73475 0.56233

The zoom lens system according to the present invention is applicable to a digital input device such as a digital still camera, a digital video camera, a mobile telephone, a PDA (Personal Digital Assistance), a surveillance camera in a surveillance system, a Web camera or a vehicle-mounted camera. In particular, the present zoom lens system is suitable for an imaging device in a digital still camera, a digital video camera or the like that requires high image quality.

Details of the present invention have been described above. However, the above-mentioned description is completely illustrative from every point of view, and does not limit the scope of the present invention. Obviously, various improvements and modifications can be performed without departing from the scope of the present invention. 

1. A zoom lens system, in order from an object side to an image side, comprising at least: a first lens unit having positive optical power; a second lens unit having negative optical power; a third lens unit having negative optical power; and an aperture diaphragm, wherein at the time of zooming, the first lens unit, the second lens unit and the third lens unit move so that intervals between these lens units vary, and wherein at the time of focusing from an infinity in-focus condition to a close-point object in-focus condition, the third lens unit moves to the object side.
 2. The zoom lens system as claimed in claim 1, satisfying the following condition: 0.50<D _(FWA) /f _(W)<2.00   (7) (here, f_(T)/f_(W)>3.0) where, D_(FWA) is an axial interval from the vertex of a surface on the most image side of the focusing lens unit to the aperture diaphragm, f_(T) is a focal length of the entire system at a telephoto limit, and f_(W) is focal length of the entire system at a wide-angle limit.
 3. The zoom lens system as claimed in claim 1, satisfying the following condition: 0.10<(D _(F) /f _(W))*(f _(T) /f _(W))<2.00   (8) (here, f_(T)/f_(W)>3.0) where, D_(F) is an axial thickness of the focusing lens unit, f_(T) is a focal length of the entire system at a telephoto limit, and f_(W) is focal length of the entire system at a wide-angle limit.
 4. The zoom lens system as claimed in claim 1, satisfying the following condition: 0.02<|D _(F) /f _(F)|<0.15   (9) (here, f_(T)/f_(W)>3.0) where, D_(F) is an axial thickness of the focusing lens unit, f_(F) is a focal length of the focusing lens unit, f_(T) is a focal length of the entire system at a telephoto limit, and f_(W) is focal length of the entire system at a wide-angle limit.
 5. The zoom lens system as claimed in claim 1, satisfying the following condition: 1.80<|f ₁ /f ₂|4.00   (10) where, f₁ is a focal length of the positive lens unit, and f₂ is a focal length of the negative lens unit.
 6. The zoom lens system as claimed in claim 1, satisfying the following condition: 0.40<|f ₂ /f _(F)|<1.80   (11) where, f₂ is a focal length of the negative lens unit, and f_(F) is a focal length of the focusing lens unit.
 7. The zoom lens system as claimed in claim 1, satisfying the following condition: 1.50<|f ₁ /f _(F)|<4.00   (12) where, f₁ is a focal length of the lens unit having positive optical power, and f_(F) is a focal length of the focusing lens unit.
 8. The zoom lens system as claimed in claim 1, satisfying the following condition: 0.40<(r _(EF) −r _(IF))/(r _(EF) +r _(IF))<2.20   (13) where, r_(IF) is a radius of paraxial curvature of the most object side surface of the focusing lens unit, and r_(EF) is a radius of paraxial curvature of the most image side surface of the focusing lens unit.
 9. An interchangeable lens apparatus comprising: a zoom lens system; and a camera mount section connected to a camera body provided with an image sensor for receiving an optical image formed by the zoom lens system and then converting the optical image into an electric image signal, wherein the zoom lens system, in order from an object side to an image side, comprises at least: a first lens unit having positive optical power; a second lens unit having negative optical power; a third lens unit having negative optical power; and an aperture diaphragm, at the time of zooming, the first lens unit, the second lens unit and the third lens unit move so that intervals between these lens units vary, and at the time of focusing from an infinity in-focus condition to a close-point object in-focus condition, the third lens unit moves to the object side.
 10. A camera system comprising: an interchangeable lens apparatus that includes a zoom lens system; and a camera body that is connected to the interchangeable lens apparatus via a camera mount section in an attachable and detachable manner and that includes an image sensor for receiving an optical image formed by the zoom lens system and then converting the optical image into an electric image signal, wherein the zoom lens system, in order from an object side to an image side, comprises at least: a first lens unit having positive optical power; a second lens unit having negative optical power; a third lens unit having negative optical power; and an aperture diaphragm, at the time of zooming, the first lens unit, the second lens unit and the third lens unit move so that intervals between these lens units vary, and at the time of focusing from an infinity in-focus condition to a close-point object in-focus condition, the third lens unit moves to the object side. 